Hi Ard,
Thanks for your response on this patch. Please see my reply inline...
On 8/30/2023 8:10 PM, Ard Biesheuvel wrote:
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On Wed, 16 Aug 2023 at 10:56, Nhi Pham <n...@amperemail.onmicrosoft.com> wrote:
Hi Ard and Ming,
I have been seeing an issue with StandaloneMM HobLib that can be fixed
by this patch as well.
The function CreateHob() in the HobLib instance
StandaloneMmPkg/Library/StandaloneMmCoreHobLib/StandaloneMmCoreHobLib.inf
does not work at all. The HobList is early created by the
StandaloneMmCoreEntryPoint then it is relocated on the heap memory by
StandaloneMmCore. But the FreeMemoryTop and FreeMemoryBottom are not
updated accordingly and the HOB free memory top is overlapped with the
heap space. This causes the CreateHob() function to not work as
expected. Introducing the PcdMemoryHobSize is reasonable to fix this issue.
I tested this patch in my end.
Tested-by: Nhi Pham <n...@os.amperecomputing.com>
Thanks for reminding me.
So if the HOB creation is completely broken, are we sure this is the
correct fix? Wouldn't it be better to update FreeMemoryTop and
FreeMemoryBottom to the correct values?
Per your question, I had a deep dive into the HOB today. I think I need
to clarify further the issue to make sure that we are on the same page.
1. When the base of the HOB list (HobStart) is reallocated in the MM
heap memory, the Hob->EfiEndOfHobList must be adjusted accordingly
compared to the new HOB base. Currently, we are missing that. That
causes the CreateHob() function does not work. The GetNextHob() function
always look up the old HOB list instead of the new HOB list.
2. The Memory Allocation StandaloneMmPkg/Core/Page.c does not update the
Hob->EfiFreeMemoryTop, this may cause the MM heap space and HOB space to
be overlapped at some points.
It sounds like the issue on the memory allocation in StandaloneMM. For
#1, I think we should write a new patch for it. For #2, could you advise?
Thanks,
-Nhi
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