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May 14th, 2014 03:00

Enabling Memory Mapped IO > 4GB has issues on R720

Hello,

We have a PCI card which needs to expose 2GB of memory to the host. When we enable the "Memory Mapped IO > 4B"  option in the BIOS, the system goes into continuous reboot cycles. When we disable it, the memory is not exposed as expected. 

Could someone please help me to resolve this issue?

Thanks,

Sarma

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8.4K Posts

May 14th, 2014 06:00

Ganesri,

First thing I would look at with the issue you are having is the BIOS version. MMIO support was added in a later update I believe was version 1.6.0.. Are you current on the systems updates? If not I would go ahead and update the server to current and see if the issue continues.

http://www.dell.com/support/home/us/en/19/product-support/product/poweredge-r720#poweredge-r720/drivers?&_suid=140006892416408658142924641785

Let me know what you find.

2 Posts

May 14th, 2014 06:00

Chris,

We have updated the BIOS, and it is on the latest version. Still we are seeing this issue. Please let me know what else we can do to overcome the problem. 

Thanks,

Sarma

1 Message

July 28th, 2014 06:00

I have exactly the same problem on T620 with bios 1.4.7 .. I updated the bios to latest version 2.2.3 and now the memory is never mapped over 4G even when I choose the option in the BIOS !!!


Any help ?

Thanks

1 Message

August 9th, 2016 22:00

has anyone WA this issue?

i'm working with R720 servers, BIOS (version 2.5.4) is configured to SR-IOV enabled and MMIO above 4G, when enableing SR-IOV for memory hungry devices (large PCI BARs for PF and VFs) i'm getting the following in dmesg:

[Wed Aug 10 07:53:32 2016] pci 0000:42:00.0: can't claim BAR 0 [mem 0xfc000000-0xfdffffff 64bit pref]: no compatible bridge window
[Wed Aug 10 07:53:32 2016] pci 0000:42:00.0: can't claim BAR 7 [mem 0xa0000000-0xbfffffff 64bit pref]: no compatible bridge window
[Wed Aug 10 07:53:32 2016] pci 0000:42:00.1: can't claim BAR 0 [mem 0xfe000000-0xffffffff 64bit pref]: no compatible bridge window
[Wed Aug 10 07:53:32 2016] pci 0000:42:00.1: can't claim BAR 7 [mem 0xc0000000-0xdfffffff 64bit pref]: no compatible bridge window

1 Message

September 19th, 2019 20:00

Turn your bios in legacy mode operation

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