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ganesri
1 Copper

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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4 Replies
Moderator
Moderator

RE: Enabling Memory Mapped IO > 4GB has issues on R720

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/driv...

Let me know what you find.

Chris Hawk

Dell | Social Outreach Services - Enterprise
Get Support on Twitter @DellCaresPro 
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ganesri
1 Copper

RE: Enabling Memory Mapped IO > 4GB has issues on R720

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

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johnf2003
1 Copper

RE: Enabling Memory Mapped IO > 4GB has issues on R720

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

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avivbarnea
1 Copper

RE: Enabling Memory Mapped IO > 4GB has issues on R720

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

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