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aarch64: page-align the UEFI loader image - #2182
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In both the commit message and the PR description, the statement "The header grows into the space .text no longer occupies, so the loader does not get any larger" is wrong and misleading. The loader is keeping the previous size just by chance. Remove all mentions of the loader size.
The PE header declares a SectionAlignment and a FileAlignment of 0x1000, and every field that locates .text is _start - IMAGE_BASE: SizeOfHeaders, AddressOfEntryPoint, BaseOfCode, and the section's VirtualAddress and PointerToRawData. With _start aligned to 8 those fields read 0x200, which the format does not allow of either a section's virtual address or SizeOfHeaders. Firmware that enforces the alignment when it applies memory attributes to a loaded image rejects the loader and asserts in DxeCore before it runs; the edk2 build Oracle Cloud Infrastructure ships as of 2026-05-22 does. Aligning _start to a page makes the declared and actual layout agree.
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The PE header of the aarch64 UEFI loader declares a SectionAlignment and a
FileAlignment of 0x1000, but _start is aligned to 8, so SizeOfHeaders and the
virtual address of .text both come out as 0x200. The format does not allow
either of them to be unaligned with respect to the values declared above.
Firmware that enforces this when it applies memory attributes to a loaded image
rejects the loader before it runs. The edk2 build that Oracle Cloud
Infrastructure ships as of 2026-05-22 asserts in DxeCore:
Aligning _start to a page makes the declared and the actual layout agree. Every
field that locates .text derives from _start - IMAGE_BASE, so they all move
together.
Tested on a VM.Standard.A1.Flex instance in eu-milan-1. Before the change the
firmware asserts as above; after it, the loader runs and reaches
ExitBootServices.
Console of the instance, captured with oci compute console-history, before the
change:
The same image on a 1 OCPU / 1 GB shape fails identically, only the address
differs (0x7E358000), so the shape of the instance is not a factor.
After the change, on the same shape, the firmware starts the image and the
loader reaches the end of its work:
Header fields before and after, read from the built binary: