I came across L551/L702 [1][5] where the alignment is set to 0x1000 (4K) if the alignment is zero. Any value other than 0 will pass through even if invalid by the UEFI specification [2]. I am curious on the reasoning behind how 0 is chosen for comparison. I have read through a similar discussion on edk2 [3] and understand this applies to x86-64. [4] Some time back, when reviewing KVM hypervisor boot logs for a Windows Server 2019/2022 VM using vTPM that was stuck in a boot loop, I saw 0x40 being passed and the sectionalignment with errors of a invalid passed value.
I am willing to provide logs. Please let me know if there are flaws in my thinking. Appreciate any help.
I see @vathpela @bluca have worked on this recently.
[1] https://git.proxmox.com/?p=efi-boot...5c44ef83e3cd3974f047343d99906b6989bbb;hb=HEAD
[2] https://uefi.org/specs/UEFI/2.9_A/07_Services_Boot_Services.html#efi-boot-services-allocatepages
[3] https://edk2.groups.io/g/devel/topic/linker_scripts_use_of_z/98045342
[4] llvm/llvm-project#117103
[5] https://github.com/rhboot/shim/blob/main/pe.c#L702
I came across L551/L702 [1][5] where the alignment is set to 0x1000 (4K) if the alignment is zero. Any value other than 0 will pass through even if invalid by the UEFI specification [2]. I am curious on the reasoning behind how 0 is chosen for comparison. I have read through a similar discussion on edk2 [3] and understand this applies to x86-64. [4] Some time back, when reviewing KVM hypervisor boot logs for a Windows Server 2019/2022 VM using vTPM that was stuck in a boot loop, I saw 0x40 being passed and the sectionalignment with errors of a invalid passed value.
I am willing to provide logs. Please let me know if there are flaws in my thinking. Appreciate any help.
I see @vathpela @bluca have worked on this recently.
[1] https://git.proxmox.com/?p=efi-boot...5c44ef83e3cd3974f047343d99906b6989bbb;hb=HEAD
[2] https://uefi.org/specs/UEFI/2.9_A/07_Services_Boot_Services.html#efi-boot-services-allocatepages
[3] https://edk2.groups.io/g/devel/topic/linker_scripts_use_of_z/98045342
[4] llvm/llvm-project#117103
[5] https://github.com/rhboot/shim/blob/main/pe.c#L702