DxeCore allocates way too much memory (Bugzilla Bug 295)

[tianocore-issues]

This issue was created automatically with bugzilla2github

Bugzilla Bug 295

Date: 2016-12-15T00:26:01+00:00
From: Michael Zimmermann <>
To: @lzeng14
CC: nobody, yonghong.zhu

Last updated: 2016-12-15T19:05:45+00:00

[tianocore-issues]

Comment 1166

Date: 2016-12-15 00:26:01 +0000
From: Michael Zimmermann <>

• Industry Specification: ---
• Releases to Fix: EDK II Master
• Target OS: ---
• Bugzilla Assignee(s): @lzeng14

Apparently, DxeCore takes the highest memory descriptor which is big enough and allocates it completely.

So if I have one memory resource descriptor for 0x80000000-0xffffffff then DxeCore allocates almost all of it(excluding the stack I guess).
In the debug log it looks like this:

CoreInitializeMemoryServices:
BaseAddress - 0x80000000 Length - 0x7E000000 MinimalMemorySizeNeeded - 0x501A000

and later on this range gets allocated:
GCD:AllocateMemorySpace(Base=0000000080000000,Length=000000007E000000) GcdAllocateType = AtAddress
GcdMemoryType = SystemMem
Alignment = 0000000000000001
ImageHandle = FDE28F90
DeviceHandle = 0
Status = Success (BaseAddress = 0000000080000000)
GCDMemType Range Capabilities Attributes
========== ================================= ================ ================
NonExist 0000000000000000-000000007FFFFFFF 0000000000000000 0000000000000000
SystemMem 0000000080000000-00000000FDFFFFFF 800000000000000E 0000000000000000*
NonExist 00000000FE000000-00000000FE3FFFFF 0000000000000000 0000000000000000
SystemMem 00000000FE400000-00000000FFFFFFFF 800000000000000E 0000000000000000

All of this is not a problem until I try to reserve smaller chunks of memory using memory allocation hobs pre-DxeCore because these will be allocated after DxeCore's giant allocation.

[tianocore-issues]

Comment 1167

Date: 2016-12-15 00:34:21 +0000
From: nobody <>

DxeCore CoreInitializeMemoryServices() tries to find the highest available memory range as the first allocated memory region. But, it doesn't consider the allocation memory hob. In the submitter's case, the highest chunk memory range is reserved as the allocation memory hob in PEI phase. DxeCore still allocates it to rewrite the memory resource.

[tianocore-issues]

Comment 1168

Date: 2016-12-15 00:47:43 +0000
From: Michael Zimmermann <>

I think this could be solved by processing the memory allocation hob's at the very beginning.
I currently have 4 other allocations before the Hob's are processed which means that there are many possibilities for accidentally allocating reserved memory depending on what your layout looks like.

[tianocore-issues]

Comment 1172

Date: 2016-12-15 19:05:45 +0000
From: Yonghong Zhu <<yonghong.zhu>>

Bug scrub: Assign to module owner