The Kaby Lake and Cannon Lake CPUs in this model line support only Windows 10 -- this isn't a Dell issue - it's a Microsoft issue. There is no support for anything older than Windows 10 beyond the sixth-generation Skylake CPUs.
Thanks for your response. The legacy OS that I'm trying to boot should be irrelevant for this conversation. I understand that Dell can always take the side of "oh well, we never advertised that we would support such an OS, so tough luck".
I've heard that newer Intel chips don't support legacy booting. However, the fact is, I can boot the legacy OS off of an external USB stick perfectly fine with this laptop. So why prevent it from working on an internal drive?
If I couldn't boot a legacy OS off of an external drive then I would be satisfied with the argument that "well, newer processors don't support legacy booting".
The OS you're trying to load DOES matter -- and loading a limited driver set for flash drive boot is completely different that loading a full set of drivers for running an OS in fully protected mode.
There are a number of pieces of hardware that Windows 7, for instance, does not have full support for (video being one major one with the eighth-generation CPU platform). Windows 7 doesn't fully support NVMe drives, as well. Further, Microsoft is blocking Windows updates for Windows 7 and 8 on Kaby Lake and Cannon Lake platforms:
And yes, there are currently hacks that unblock the Windows update issue -- for now -- Microsoft will simply disable the hacks as we go along, or leave it for now - remember, within two years, Windows 7 goes completely end of life.
Bottom line: you can hack your way into Windows 7 or 8 on Kaby or Cannon Lake for now, but that hack is only temporary. Within the lifecycle of any new system, Windows 7 will go dark -- meaning it's just a stopgap.
Microsoft is not supporting anything older than Windows 10 on any platform after Skylake - period. If you need "legacy" OS support, you need a Skylake or earlier system. And whatever your reasons for needing that legacy OS, you'll need to resolve those before January 2020 - when Windows 7 goes dark.
Thank you for taking the time to respond. I really appreciate it.
I can see from a business perspective why Dell would want to block consumers from trying to boot an OS in legacy mode on the internal drive but allow it on external drives. There may be some handy tools that users could boot on external drives in legacy mode only (for example, maybe for BIOS updates or cloning drives). However, if a user is booting an OS from an internal drive in legacy mode then it implies that they're using an obsolete OS as their main OS that is likely end-of-life, littered with security holes, and has broken or missing drivers that would severely impact their usability and online security. This would also likely result in countless tech support questions to Dell (which wastes time and money). So overall, it sounds like it would be best for the end consumer and Dell (win-win).
So if I understand correctly, Dell isn't preventing legacy boot from an internal drive for a technical reason, but for a business reason. Similarly, I wouldn't be surprised if Microsoft is pushing Dell (and probably other manufacturers) to prevent users from installing older Microsoft Operating Systems so that they don't have to support them or deal with them anymore.
However, we want to install a real-time OS (not Windows or Linux) on the amazing hardware that Dell makes. Whatever drivers this OS is using when booted from a flash drive allow us to use the computer fully for our use case and we have no issues (other than it was booted from a USB stick). It also does not connect to any networks so we have no concerns about security.
I imagine that it's just a very simple modification in the UEFI firmware to prevent booting an OS in legacy mode from an internal drive. Would it be possible to get a custom UEFI firmware from Dell that disables this "feature"?
As a side note, we're able to do the following, which is why I strongly believe it's just a UEFI firmware limitation that Dell implemented (and perhaps this loophole was overlooked):
- put the 7490 firmware in "legacy mode" (which potentially might not even exist in the near future)
- install rEFInd on a USB stick
- boot the laptop but select rEFInd in "UEFI USB device" instead of "legacy USB device" from the Dell boot menu
- rEFInd sees the OS on the internal drive and boots it in legacy mode, perfectly fine, no issues
However, if we boot rEFInd when the laptop's firmware is set to "UEFI mode" then it can't find the internal OS to boot (which makes sense, since rEFInd relies on UEFI to find legacy devices to boot).
A few questions here since this discussion may have gone a bit off into the weeds:
You say it boots Legacy mode from a USB drive just fine. As ejn63 points out, not all OSes are the same, and at least in the Windows side, booting from a flash drive is a particularly poor test because "Windows" booted from a flash drive is just Windows PE, not full Windows, and the ability to boot Windows PE from a flash drive does not always mean that the corresponding "full" Windows version will boot when installed onto the system. However, some OSes like Linux allow a "full OS" to be booted from USB, so my first question is: Are you saying that while you can't boot your desired OS from an internal drive, you can boot that exact same OS from a flash drive? If so, then that clearly establishes that Legacy booting is supported, and the system supports your Legacy-based OS. In that case, unless there is indeed a firmware-level restriction saying, "Even when Legacy boot is enabled, only allow Legacy boot from USB devices", which is something I've never encountered or even read about, then I don't think firmware is your problem. I haven't gotten my hands on a Latitude 7490 yet, but I really doubt that restriction would exist. But if it does, your prospects of getting custom firmware are realistically zero.
However, it's very possible that something else is the issue, quite possibly the driver/OS support for the storage interface. Your BIOS Setup interface should have options to place the internal storage in AHCI or RAID mode. If you use the former, your OS would need to have native support for NVMe (assuming you're using an NVMe/PCIe SSD rather than a SATA SSD). If you use the latter, the OS will need to have (or you will need to provide) a sufficiently new version of the Intel Rapid Storage Technology driver, since RAID mode places the internal storage interface behind that controller even if you have no intention of using actual RAID. Of course if you're booting from USB, access to the internal storage isn't an issue, which could explain the difference.
Out of curiosity, what actually happens when you try to boot this OS in Legacy mode? You just said that it won't boot it; that's not very specific if you're trying to get troubleshooting assistance.
(Trying again since my post seems to keep disappearing a few minutes after it's accepted....)
It looks like this discussion may have gone a bit off into the weeds, so I wanted to provide a bit of background, ask a key question, and make a suggestion.
First, you say your OS boots in Legacy mode from a USB drive just fine. As ejn63 points out, USB booting is not always a reliable test, especially in the Windows world because booting "Windows" from a flash drive is almost always just Windows PE, not full Windows, and the ability to boot Windows PE from a flash drive does not always mean that the corresponding "full" Windows version will boot when installed onto the system.
However, you're apparently not using Windows, and some OSes like Linux DO in fact allow the full OS to be booted from USB, so the key question is: Are you saying that while you can't boot your desired OS from an internal drive, you can boot that exact same OS from a flash drive? If so, then that clearly establishes both that Legacy booting is supported, and that the system will run your Legacy-based OS. In that case, unless there is indeed a firmware-level restriction saying, "Even when Legacy boot is enabled, only allow Legacy boot from USB devices", which is something I've never encountered or even read about, then I don't think firmware is your problem. I haven't gotten my hands on a Latitude 7490 yet, but I really doubt that restriction would exist. But if it does, your prospects of getting custom firmware are realistically zero.
However, it's very possible that something else is the issue, quite possibly the driver/OS support for the storage interface. Your BIOS Setup interface should have options to place the internal storage in AHCI or RAID mode. If you use the former, your OS would need to have native support for NVMe (assuming you're using an NVMe/PCIe SSD rather than a SATA SSD). If you use the latter, the OS will need to have (or you will need to provide) a sufficiently new version of the Intel Rapid Storage Technology driver, since RAID mode places the internal storage interface behind that controller even if you have no intention of using actual RAID. Of course if you're booting from USB, access to the internal storage isn't an issue, which could explain the difference.
Out of curiosity, what actually happens when you try to boot this OS in Legacy mode? You just said that it won't boot it; that's not very specific if you're trying to get troubleshooting assistance.
A few questions here since this discussion may have gone a bit off into the weeds:
You say your OS boots in Legacy mode from a USB drive just fine. As ejn63 points out, not all OSes are the same, and it's a particularly reasonable mention because in the Windows world, booting from a flash drive is a particularly poor test because "Windows" when booted from a flash drive is almost always just Windows PE, not full Windows, and the ability to boot Windows PE from a flash drive does not always mean that the corresponding "full" Windows version will boot when installed onto the system.
However, some OSes like Linux allow the full OS to be booted from USB, so my main question is: Are you saying that while you can't boot your desired OS from an internal drive, you can boot that exact same OS from a flash drive? If so, then that clearly establishes both that Legacy booting is supported, and that the system will run your Legacy-based OS. In that case, unless there is indeed a firmware-level restriction saying, "Even when Legacy boot is enabled, only allow Legacy boot from USB devices", which is something I've never encountered or even read about, then I don't think firmware is your problem. I haven't gotten my hands on a Latitude 7490 yet, but I really doubt that restriction would exist. But if it does, your prospects of getting custom firmware are realistically zero.
However, it's very possible that something else is the issue, quite possibly the driver/OS support for the storage interface. Your BIOS Setup interface should have options to place the internal storage in AHCI or RAID mode. If you use the former, your OS would need to have native support for NVMe (assuming you're using an NVMe/PCIe SSD rather than a SATA SSD). If you use the latter, the OS will need to have (or you will need to provide) a sufficiently new version of the Intel Rapid Storage Technology driver, since RAID mode places the internal storage interface behind that controller even if you have no intention of using actual RAID. Of course if you're booting from USB, access to the internal storage isn't an issue, which could explain the difference.
Out of curiosity, what actually happens when you try to boot this OS in Legacy mode? You just said that it won't boot it; that's not very specific if you're trying to get troubleshooting assistance.
The other issue is that this is a VERY new system, and unless rEFInd has been updated, may need to be rebuilt or recompiled to work with the new hardware. Any changes to boot/no boot will need to come from rEFInd -- not from Dell.
I don't think this is a block on booting a non-Windows OS -- yes, that can be done -- but it's not something Dell is doing with at least most of its systems -- since Linux is an option on a large number of them.
It is VERY true that Windows 10 updates CAN disable Grub (and simlar) boot managers -- that's just the nature of things (at least until new releases of the OS come around).
I think that there has been a bit of a miscommunication here.
The Dell Latitude 7490 has two modes, UEFI boot and Legacy boot.
When set to Legacy boot, it lists only external devices as options to boot from, for example: USB, SD card. The internal drive is NOT listed. I can't even attempt to boot the OS in legacy mode from the internal drive as the UEFI firmware will not list it in the list of devices to boot from (when in Legacy boot mode).
If I set it to Legacy boot mode, then I can see the rEFInd USB stick as two options in the boot menu. One is shown in Legacy and the other is UEFI (even though the laptop is in Legacy boot mode). If I select the UEFI USB stick option, then rEFInd finds the internal drive and lets me boot the OS in legacy mode, and everything works flawlessly.
If I boot rEFInd when the firmware is set to UEFI mode then it can't find the legacy OS to boot on the internal drive.
Similarly, if I install the legacy OS on a USB stick, set the laptop to Legacy mode, then when I boot the laptop it shows up in the boot menu as a Legacy option. I can boot it and everything runs flawlessly.
This is news to me too which is why I'm reaching out for help. I can't believe that Dell would prevent booting a legacy OS from an internal drive but allow it from an external drive and I suspect that you won't believe it either. By preventing, I mean that they don't even give the option to select the internal drive to boot when in Legacy mode. Although, as I mentioned in a previous post, maybe Dell is doing this as a business strategy (or an agreement with Microsoft). So I'll see if I can take some pictures of the firmware settings and post them here, it's really quite surprising.
The Dell options in the UEFI firmware even state something along the lines of "Note: If you select Legacy mode then you will only be allowed to boot a Legacy mode OS from an external device. You will be prevented from booting a Legacy mode OS from an internal device.".
I hope that we're on the same page now. If I can get some pictures on here then I think it will clarify things further.
Just a quick update, the BIOS version on this Dell Latitude 7490 is 1.1.6.
Boot List Options in UEFI firmware are:
1) Legacy External Devices
2) UEFI
When Legacy External Devices is selected, then the list of options becomes (note no internal drive):
- Diskette Drive (even though it doesn't have a floppy drive)
- USB Storage Device
- CD/DVD/CD-RW Drive (even though it doesn't have an optical drive)
- Onboard NIC
Under Advanced Boot Options it states:
"Legacy External Devices boot mode does not support OS boot on internal storage devices such as HDD, SSD, NVMe, or eMMC. It is intended for use with external storage devices only, such as SD Card, USB, and Network PXE."
Unfortunately for me, this means that if I want to boot this real-time OS off the internal drive on this laptop I need to get a UEFI compliant version of it, which also means that I'll need to port an entire code base to 64-bit (as very few laptops support 32-bit UEFI booting). I don't want to get into 32-bit vs. 64-bit UEFI booting as that's an entirely different can of worms. Without going into technical details, no, it's not just a matter of recompiling for 64-bit.
I guess I should have been more careful in my wording. The real questions are:
1) Why does Dell purposely block booting a legacy OS off of the internal drive but allow it on external drives?
I suspect now that this is to limit technical support calls to Dell and also ensure that the average consumer is using a modern OS as their primary OS on this laptop (or to satisfy some agreement with Microsoft). However, it's unfortunate that it would likely work perfectly fine and Dell is not even giving consumers the choice now. It just means that in the short term future I can't use the 7490 for my specific scenario (and will need to try alternative manufacturer's laptops as it's a lot cheaper than porting 32-bit code to 64-bit code).
2) Is there a way around this and can Dell provide a UEFI firmware update to allow booting a legacy OS off of an internal drive?
WOW! Ok, previous Dell systems have just said "Legacy" where you're seeing "Legacy External Devices". Given that wording change, that makes it pretty clear that Dell has in fact decided to limit Legacy boot capability only to external devices, not internal drives. I'm stunned. As to why, limiting support calls is certainly a possibility (there are plenty of threads here with people complaining that they can't get Windows 7 to run on systems that were never meant to support Win7, after all), and/or there may be technical reasons. For example, the 7490 may have hardware that no longer has Option ROMs and therefore would not run be usable under "full" Windows, but that hardware may not be needed in the typical environments people would boot from a flash drive. I suspect the reason Dell didn't remove Legacy booting entirely is that there are several recovery utilities and such that probably don't support UEFI yet but that people like to use, even if they don't ever need to install a full Legacy OS onto their hardware.
Anyhow, getting custom firmware as I said is realistically impossible. Firmware updates have to be signed by Dell in order to be accepted by the system. Given that Dell clearly made a deliberate change here, I don't see them offering a **bleep** firmware build upon request. MAYBE if you were a huge customer of theirs, but even then I rather doubt it. So unless you can find a way to work around the signature requirement (or forge it) AND you can develop custom firmware for this system yourself, you'd be stuck.
All that said, the Latitude 7480 is still available for purchase and it definitely supports Legacy booting from internal drives, just in case the changes made for the 7490 aren't especially important to you.
I ran into the same issue with my new 7490 today, and I was able to get the OS to install & boot with SATA configured with AHCI instead of RAID on. Once I switched to AHCI, I was able to boot to the SSD just fine. What do you have the SATA configured to currently?
Fyi, not that it matters, but you could have gotten the OS to install with RAID on had you supplied the necessary Intel Rapid Storage Technology driver while installing the OS, but AHCI is certainly simpler for Windows 10, and the only reason to use RAID in that case would be on systems that had a spinning hard drive plus a small SSD that was intended to be used as a cache module for it.
ejn63
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February 2nd, 2018 13:00
What "legacy" OS are you trying to boot?
The Kaby Lake and Cannon Lake CPUs in this model line support only Windows 10 -- this isn't a Dell issue - it's a Microsoft issue. There is no support for anything older than Windows 10 beyond the sixth-generation Skylake CPUs.
http://www.dell.com/support/article/us/en/04/sln304217/microsoft-windows-operating-system-support-for-intel-kaby-lake-processors?lang=en
legacy_boot
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February 2nd, 2018 13:00
Hey,
Thanks for your response. The legacy OS that I'm trying to boot should be irrelevant for this conversation. I understand that Dell can always take the side of "oh well, we never advertised that we would support such an OS, so tough luck".
I've heard that newer Intel chips don't support legacy booting. However, the fact is, I can boot the legacy OS off of an external USB stick perfectly fine with this laptop. So why prevent it from working on an internal drive?
If I couldn't boot a legacy OS off of an external drive then I would be satisfied with the argument that "well, newer processors don't support legacy booting".
Cheers
ejn63
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February 2nd, 2018 14:00
The OS you're trying to load DOES matter -- and loading a limited driver set for flash drive boot is completely different that loading a full set of drivers for running an OS in fully protected mode.
There are a number of pieces of hardware that Windows 7, for instance, does not have full support for (video being one major one with the eighth-generation CPU platform). Windows 7 doesn't fully support NVMe drives, as well. Further, Microsoft is blocking Windows updates for Windows 7 and 8 on Kaby Lake and Cannon Lake platforms:
https://support.microsoft.com/en-us/help/4012982/the-processor-is-not-supported-together-with-the-windows-version-that
And yes, there are currently hacks that unblock the Windows update issue -- for now -- Microsoft will simply disable the hacks as we go along, or leave it for now - remember, within two years, Windows 7 goes completely end of life.
Bottom line: you can hack your way into Windows 7 or 8 on Kaby or Cannon Lake for now, but that hack is only temporary. Within the lifecycle of any new system, Windows 7 will go dark -- meaning it's just a stopgap.
Microsoft is not supporting anything older than Windows 10 on any platform after Skylake - period. If you need "legacy" OS support, you need a Skylake or earlier system. And whatever your reasons for needing that legacy OS, you'll need to resolve those before January 2020 - when Windows 7 goes dark.
legacy_boot
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February 5th, 2018 12:00
Hi ejn63,
Thank you for taking the time to respond. I really appreciate it.
I can see from a business perspective why Dell would want to block consumers from trying to boot an OS in legacy mode on the internal drive but allow it on external drives. There may be some handy tools that users could boot on external drives in legacy mode only (for example, maybe for BIOS updates or cloning drives). However, if a user is booting an OS from an internal drive in legacy mode then it implies that they're using an obsolete OS as their main OS that is likely end-of-life, littered with security holes, and has broken or missing drivers that would severely impact their usability and online security. This would also likely result in countless tech support questions to Dell (which wastes time and money). So overall, it sounds like it would be best for the end consumer and Dell (win-win).
So if I understand correctly, Dell isn't preventing legacy boot from an internal drive for a technical reason, but for a business reason. Similarly, I wouldn't be surprised if Microsoft is pushing Dell (and probably other manufacturers) to prevent users from installing older Microsoft Operating Systems so that they don't have to support them or deal with them anymore.
However, we want to install a real-time OS (not Windows or Linux) on the amazing hardware that Dell makes. Whatever drivers this OS is using when booted from a flash drive allow us to use the computer fully for our use case and we have no issues (other than it was booted from a USB stick). It also does not connect to any networks so we have no concerns about security.
I imagine that it's just a very simple modification in the UEFI firmware to prevent booting an OS in legacy mode from an internal drive. Would it be possible to get a custom UEFI firmware from Dell that disables this "feature"?
As a side note, we're able to do the following, which is why I strongly believe it's just a UEFI firmware limitation that Dell implemented (and perhaps this loophole was overlooked):
- put the 7490 firmware in "legacy mode" (which potentially might not even exist in the near future)
- install rEFInd on a USB stick
- boot the laptop but select rEFInd in "UEFI USB device" instead of "legacy USB device" from the Dell boot menu
- rEFInd sees the OS on the internal drive and boots it in legacy mode, perfectly fine, no issues
However, if we boot rEFInd when the laptop's firmware is set to "UEFI mode" then it can't find the internal OS to boot (which makes sense, since rEFInd relies on UEFI to find legacy devices to boot).
Thanks again.
jphughan
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February 5th, 2018 13:00
A few questions here since this discussion may have gone a bit off into the weeds:
You say it boots Legacy mode from a USB drive just fine. As ejn63 points out, not all OSes are the same, and at least in the Windows side, booting from a flash drive is a particularly poor test because "Windows" booted from a flash drive is just Windows PE, not full Windows, and the ability to boot Windows PE from a flash drive does not always mean that the corresponding "full" Windows version will boot when installed onto the system. However, some OSes like Linux allow a "full OS" to be booted from USB, so my first question is: Are you saying that while you can't boot your desired OS from an internal drive, you can boot that exact same OS from a flash drive? If so, then that clearly establishes that Legacy booting is supported, and the system supports your Legacy-based OS. In that case, unless there is indeed a firmware-level restriction saying, "Even when Legacy boot is enabled, only allow Legacy boot from USB devices", which is something I've never encountered or even read about, then I don't think firmware is your problem. I haven't gotten my hands on a Latitude 7490 yet, but I really doubt that restriction would exist. But if it does, your prospects of getting custom firmware are realistically zero.
However, it's very possible that something else is the issue, quite possibly the driver/OS support for the storage interface. Your BIOS Setup interface should have options to place the internal storage in AHCI or RAID mode. If you use the former, your OS would need to have native support for NVMe (assuming you're using an NVMe/PCIe SSD rather than a SATA SSD). If you use the latter, the OS will need to have (or you will need to provide) a sufficiently new version of the Intel Rapid Storage Technology driver, since RAID mode places the internal storage interface behind that controller even if you have no intention of using actual RAID. Of course if you're booting from USB, access to the internal storage isn't an issue, which could explain the difference.
Out of curiosity, what actually happens when you try to boot this OS in Legacy mode? You just said that it won't boot it; that's not very specific if you're trying to get troubleshooting assistance.
jphughan
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February 5th, 2018 14:00
(Trying again since my post seems to keep disappearing a few minutes after it's accepted....)
It looks like this discussion may have gone a bit off into the weeds, so I wanted to provide a bit of background, ask a key question, and make a suggestion.
First, you say your OS boots in Legacy mode from a USB drive just fine. As ejn63 points out, USB booting is not always a reliable test, especially in the Windows world because booting "Windows" from a flash drive is almost always just Windows PE, not full Windows, and the ability to boot Windows PE from a flash drive does not always mean that the corresponding "full" Windows version will boot when installed onto the system.
However, you're apparently not using Windows, and some OSes like Linux DO in fact allow the full OS to be booted from USB, so the key question is: Are you saying that while you can't boot your desired OS from an internal drive, you can boot that exact same OS from a flash drive? If so, then that clearly establishes both that Legacy booting is supported, and that the system will run your Legacy-based OS. In that case, unless there is indeed a firmware-level restriction saying, "Even when Legacy boot is enabled, only allow Legacy boot from USB devices", which is something I've never encountered or even read about, then I don't think firmware is your problem. I haven't gotten my hands on a Latitude 7490 yet, but I really doubt that restriction would exist. But if it does, your prospects of getting custom firmware are realistically zero.
However, it's very possible that something else is the issue, quite possibly the driver/OS support for the storage interface. Your BIOS Setup interface should have options to place the internal storage in AHCI or RAID mode. If you use the former, your OS would need to have native support for NVMe (assuming you're using an NVMe/PCIe SSD rather than a SATA SSD). If you use the latter, the OS will need to have (or you will need to provide) a sufficiently new version of the Intel Rapid Storage Technology driver, since RAID mode places the internal storage interface behind that controller even if you have no intention of using actual RAID. Of course if you're booting from USB, access to the internal storage isn't an issue, which could explain the difference.
Out of curiosity, what actually happens when you try to boot this OS in Legacy mode? You just said that it won't boot it; that's not very specific if you're trying to get troubleshooting assistance.
jphughan
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February 5th, 2018 14:00
A few questions here since this discussion may have gone a bit off into the weeds:
You say your OS boots in Legacy mode from a USB drive just fine. As ejn63 points out, not all OSes are the same, and it's a particularly reasonable mention because in the Windows world, booting from a flash drive is a particularly poor test because "Windows" when booted from a flash drive is almost always just Windows PE, not full Windows, and the ability to boot Windows PE from a flash drive does not always mean that the corresponding "full" Windows version will boot when installed onto the system.
However, some OSes like Linux allow the full OS to be booted from USB, so my main question is: Are you saying that while you can't boot your desired OS from an internal drive, you can boot that exact same OS from a flash drive? If so, then that clearly establishes both that Legacy booting is supported, and that the system will run your Legacy-based OS. In that case, unless there is indeed a firmware-level restriction saying, "Even when Legacy boot is enabled, only allow Legacy boot from USB devices", which is something I've never encountered or even read about, then I don't think firmware is your problem. I haven't gotten my hands on a Latitude 7490 yet, but I really doubt that restriction would exist. But if it does, your prospects of getting custom firmware are realistically zero.
However, it's very possible that something else is the issue, quite possibly the driver/OS support for the storage interface. Your BIOS Setup interface should have options to place the internal storage in AHCI or RAID mode. If you use the former, your OS would need to have native support for NVMe (assuming you're using an NVMe/PCIe SSD rather than a SATA SSD). If you use the latter, the OS will need to have (or you will need to provide) a sufficiently new version of the Intel Rapid Storage Technology driver, since RAID mode places the internal storage interface behind that controller even if you have no intention of using actual RAID. Of course if you're booting from USB, access to the internal storage isn't an issue, which could explain the difference.
Out of curiosity, what actually happens when you try to boot this OS in Legacy mode? You just said that it won't boot it; that's not very specific if you're trying to get troubleshooting assistance.
ejn63
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February 5th, 2018 17:00
The other issue is that this is a VERY new system, and unless rEFInd has been updated, may need to be rebuilt or recompiled to work with the new hardware. Any changes to boot/no boot will need to come from rEFInd -- not from Dell.
I don't think this is a block on booting a non-Windows OS -- yes, that can be done -- but it's not something Dell is doing with at least most of its systems -- since Linux is an option on a large number of them.
It is VERY true that Windows 10 updates CAN disable Grub (and simlar) boot managers -- that's just the nature of things (at least until new releases of the OS come around).
legacy_boot
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February 6th, 2018 07:00
Here's some pictures of the firmware settings on the 7490:
https://imgur.com/a/yCeHG
legacy_boot
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February 6th, 2018 07:00
Hi ejn63 and jphughan, thanks for your responses.
I think that there has been a bit of a miscommunication here.
The Dell Latitude 7490 has two modes, UEFI boot and Legacy boot.
When set to Legacy boot, it lists only external devices as options to boot from, for example: USB, SD card. The internal drive is NOT listed. I can't even attempt to boot the OS in legacy mode from the internal drive as the UEFI firmware will not list it in the list of devices to boot from (when in Legacy boot mode).
If I set it to Legacy boot mode, then I can see the rEFInd USB stick as two options in the boot menu. One is shown in Legacy and the other is UEFI (even though the laptop is in Legacy boot mode). If I select the UEFI USB stick option, then rEFInd finds the internal drive and lets me boot the OS in legacy mode, and everything works flawlessly.
If I boot rEFInd when the firmware is set to UEFI mode then it can't find the legacy OS to boot on the internal drive.
Similarly, if I install the legacy OS on a USB stick, set the laptop to Legacy mode, then when I boot the laptop it shows up in the boot menu as a Legacy option. I can boot it and everything runs flawlessly.
This is news to me too which is why I'm reaching out for help. I can't believe that Dell would prevent booting a legacy OS from an internal drive but allow it from an external drive and I suspect that you won't believe it either. By preventing, I mean that they don't even give the option to select the internal drive to boot when in Legacy mode. Although, as I mentioned in a previous post, maybe Dell is doing this as a business strategy (or an agreement with Microsoft). So I'll see if I can take some pictures of the firmware settings and post them here, it's really quite surprising.
The Dell options in the UEFI firmware even state something along the lines of "Note: If you select Legacy mode then you will only be allowed to boot a Legacy mode OS from an external device. You will be prevented from booting a Legacy mode OS from an internal device.".
I hope that we're on the same page now. If I can get some pictures on here then I think it will clarify things further.
Cheers
legacy_boot
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February 6th, 2018 07:00
Just a quick update, the BIOS version on this Dell Latitude 7490 is 1.1.6.
Boot List Options in UEFI firmware are:
1) Legacy External Devices
2) UEFI
When Legacy External Devices is selected, then the list of options becomes (note no internal drive):
- Diskette Drive (even though it doesn't have a floppy drive)
- USB Storage Device
- CD/DVD/CD-RW Drive (even though it doesn't have an optical drive)
- Onboard NIC
Under Advanced Boot Options it states:
"Legacy External Devices boot mode does not support OS boot on internal storage devices such as HDD, SSD, NVMe, or eMMC. It is intended for use with external storage devices only, such as SD Card, USB, and Network PXE."
Unfortunately for me, this means that if I want to boot this real-time OS off the internal drive on this laptop I need to get a UEFI compliant version of it, which also means that I'll need to port an entire code base to 64-bit (as very few laptops support 32-bit UEFI booting). I don't want to get into 32-bit vs. 64-bit UEFI booting as that's an entirely different can of worms. Without going into technical details, no, it's not just a matter of recompiling for 64-bit.
I guess I should have been more careful in my wording. The real questions are:
1) Why does Dell purposely block booting a legacy OS off of the internal drive but allow it on external drives?
I suspect now that this is to limit technical support calls to Dell and also ensure that the average consumer is using a modern OS as their primary OS on this laptop (or to satisfy some agreement with Microsoft). However, it's unfortunate that it would likely work perfectly fine and Dell is not even giving consumers the choice now. It just means that in the short term future I can't use the 7490 for my specific scenario (and will need to try alternative manufacturer's laptops as it's a lot cheaper than porting 32-bit code to 64-bit code).
2) Is there a way around this and can Dell provide a UEFI firmware update to allow booting a legacy OS off of an internal drive?
Cheers
jphughan
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February 6th, 2018 08:00
WOW! Ok, previous Dell systems have just said "Legacy" where you're seeing "Legacy External Devices". Given that wording change, that makes it pretty clear that Dell has in fact decided to limit Legacy boot capability only to external devices, not internal drives. I'm stunned. As to why, limiting support calls is certainly a possibility (there are plenty of threads here with people complaining that they can't get Windows 7 to run on systems that were never meant to support Win7, after all), and/or there may be technical reasons. For example, the 7490 may have hardware that no longer has Option ROMs and therefore would not run be usable under "full" Windows, but that hardware may not be needed in the typical environments people would boot from a flash drive. I suspect the reason Dell didn't remove Legacy booting entirely is that there are several recovery utilities and such that probably don't support UEFI yet but that people like to use, even if they don't ever need to install a full Legacy OS onto their hardware.
Anyhow, getting custom firmware as I said is realistically impossible. Firmware updates have to be signed by Dell in order to be accepted by the system. Given that Dell clearly made a deliberate change here, I don't see them offering a **bleep** firmware build upon request. MAYBE if you were a huge customer of theirs, but even then I rather doubt it. So unless you can find a way to work around the signature requirement (or forge it) AND you can develop custom firmware for this system yourself, you'd be stuck.
All that said, the Latitude 7480 is still available for purchase and it definitely supports Legacy booting from internal drives, just in case the changes made for the 7490 aren't especially important to you.
luckadoj
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February 8th, 2018 08:00
I ran into the same issue with my new 7490 today, and I was able to get the OS to install & boot with SATA configured with AHCI instead of RAID on. Once I switched to AHCI, I was able to boot to the SSD just fine. What do you have the SATA configured to currently?
jphughan
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February 8th, 2018 09:00
Fyi, not that it matters, but you could have gotten the OS to install with RAID on had you supplied the necessary Intel Rapid Storage Technology driver while installing the OS, but AHCI is certainly simpler for Windows 10, and the only reason to use RAID in that case would be on systems that had a spinning hard drive plus a small SSD that was intended to be used as a cache module for it.
jphughan
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February 8th, 2018 09:00
AHCI vs RAID pertains to the SATA configuration. That is completely different from UEFI vs Legacy BIOS boot mode.