What's your total RAM installed? 4G or more. With HW memory hole enable?
YH
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From: linuxbios-bounces@linuxbios.org [mailto:linuxbios-bounces@linuxbios.org] On Behalf Of Alan Mimms Sent: Wednesday, October 04, 2006 11:28 AM To: linuxbios@linuxbios.org Subject: [LinuxBIOS] ACPI NVS and last 64k-ish area of RAM?
We have AMD dual Opteron hardware with AMD 8131+8111 chipsets attached. Using LinuxBIOS, we have a slight problem, that APPEARS to be related to the last 64Kbytes of RAM. Our kboot based environment, running in 32 bit instruction set, seems to randomly crash, and the implicated area of memory is this last 64KB.
When we run a commercial BIOS on nearly identical hardware, we see that that BIOS has created in the E820 table an ACPI Non-Volatile-Storage area covering this last 64KB. LinuxBIOS is NOT doing that; LinuxBIOS is treating all of the space as simple USABLE space.
In trying to figure this out, we have used the AMD HDT tool to read the last 64KB. We (SOMETIMES) the system crashes when we read this area using HDT.
Can someone please explain what this area is for and why it's strange to read even using a hardware debugging tool? Is it REALLY in use for the ACPI NVS, and can we simply tell Linux to ignore it (map it out) by creating an entry in E820 table so it won't be used (we don't use ACPI suspend/resume)?
Thanks very much for any information.
Alan Mimms, Senior Architect F5 Networks, Inc. Spokane Development Center 1322 North Whitman Lane Liberty Lake, Washington 99019
v: 509-343-3524 f: 509-343-3501
The problem occurs with 1GB, 2GB or 4GB of memory installed for sure. I do not know about the HW memory hole. Can you explain what that is?
Alan Mimms, Senior Architect F5 Networks, Inc. Spokane Development Center 1322 North Whitman Lane Liberty Lake, Washington 99019
v: 509-343-3524 f: 509-343-3501
________________________________
From: Lu, Yinghai [mailto:yinghai.lu@amd.com] Sent: Wednesday, October 04, 2006 12:05 PM To: Alan Mimms; linuxbios@linuxbios.org; Andi Kleen Subject: RE: [LinuxBIOS] ACPI NVS and last 64k-ish area of RAM?
What's your total RAM installed? 4G or more. With HW memory hole enable?
YH
________________________________
From: linuxbios-bounces@linuxbios.org [mailto:linuxbios-bounces@linuxbios.org] On Behalf Of Alan Mimms Sent: Wednesday, October 04, 2006 11:28 AM To: linuxbios@linuxbios.org Subject: [LinuxBIOS] ACPI NVS and last 64k-ish area of RAM?
We have AMD dual Opteron hardware with AMD 8131+8111 chipsets attached. Using LinuxBIOS, we have a slight problem, that APPEARS to be related to the last 64Kbytes of RAM. Our kboot based environment, running in 32 bit instruction set, seems to randomly crash, and the implicated area of memory is this last 64KB.
When we run a commercial BIOS on nearly identical hardware, we see that that BIOS has created in the E820 table an ACPI Non-Volatile-Storage area covering this last 64KB. LinuxBIOS is NOT doing that; LinuxBIOS is treating all of the space as simple USABLE space.
In trying to figure this out, we have used the AMD HDT tool to read the last 64KB. We (SOMETIMES) the system crashes when we read this area using HDT.
Can someone please explain what this area is for and why it's strange to read even using a hardware debugging tool? Is it REALLY in use for the ACPI NVS, and can we simply tell Linux to ignore it (map it out) by creating an entry in E820 table so it won't be used (we don't use ACPI suspend/resume)?
Thanks very much for any information.
Alan Mimms, Senior Architect F5 Networks, Inc. Spokane Development Center 1322 North Whitman Lane Liberty Lake, Washington 99019
v: 509-343-3524 f: 509-343-3501
I found that the best way for me to learn about this was to play with the factory BIOS settings.
The memory hole allows you to boost part of memory above 4GB so that you have more room for I/O devices without losing memory capacity.
For example, if you had a graphics card with 256MB of memory and 4GB of RAM installed in the machine, you cannot address both and keep them inside 32-bits. The solution is to use registers on the Opteron to map some of your RAM above that limit.
Myles
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From: linuxbios-bounces@linuxbios.org [mailto:linuxbios-bounces@linuxbios.org] On Behalf Of Alan Mimms Sent: Wednesday, October 04, 2006 1:59 PM To: Lu, Yinghai; linuxbios@linuxbios.org; Andi Kleen Subject: Re: [LinuxBIOS] ACPI NVS and last 64k-ish area of RAM?
The problem occurs with 1GB, 2GB or 4GB of memory installed for sure. I do not know about the HW memory hole. Can you explain what that is?
Alan Mimms, Senior Architect F5 Networks, Inc. Spokane Development Center 1322 North Whitman Lane Liberty Lake, Washington 99019
v: 509-343-3524 f: 509-343-3501
_____
From: Lu, Yinghai [mailto:yinghai.lu@amd.com] Sent: Wednesday, October 04, 2006 12:05 PM To: Alan Mimms; linuxbios@linuxbios.org; Andi Kleen Subject: RE: [LinuxBIOS] ACPI NVS and last 64k-ish area of RAM?
What's your total RAM installed? 4G or more. With HW memory hole enable?
YH
_____
From: linuxbios-bounces@linuxbios.org [mailto:linuxbios-bounces@linuxbios.org] On Behalf Of Alan Mimms Sent: Wednesday, October 04, 2006 11:28 AM To: linuxbios@linuxbios.org Subject: [LinuxBIOS] ACPI NVS and last 64k-ish area of RAM?
We have AMD dual Opteron hardware with AMD 8131+8111 chipsets attached. Using LinuxBIOS, we have a slight problem, that APPEARS to be related to the last 64Kbytes of RAM. Our kboot based environment, running in 32 bit instruction set, seems to randomly crash, and the implicated area of memory is this last 64KB.
When we run a commercial BIOS on nearly identical hardware, we see that that BIOS has created in the E820 table an ACPI Non-Volatile-Storage area covering this last 64KB. LinuxBIOS is NOT doing that; LinuxBIOS is treating all of the space as simple USABLE space.
In trying to figure this out, we have used the AMD HDT tool to read the last 64KB. We (SOMETIMES) the system crashes when we read this area using HDT.
Can someone please explain what this area is for and why it's strange to read even using a hardware debugging tool? Is it REALLY in use for the ACPI NVS, and can we simply tell Linux to ignore it (map it out) by creating an entry in E820 table so it won't be used (we don't use ACPI suspend/resume)?
Thanks very much for any information.
Alan Mimms, Senior Architect F5 Networks, Inc. Spokane Development Center 1322 North Whitman Lane Liberty Lake, Washington 99019
v: 509-343-3524 f: 509-343-3501
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Alan Mimms -
Lu, Yinghai -
Myles Watson