Daan De Meyer
4e5c605d4b
EFI_DISK_IO_PROTOCOL (UEFI spec section 13.7, https://uefi.org/specs/UEFI/2.10/13_Protocols_Media_Access.html#disk-i-o-protocol) supports reads at arbitrary byte offsets with no alignment requirements on the buffer. The UEFI spec mandates that firmware produces this protocol on every handle that also has EFI_BLOCK_IO_PROTOCOL, so it is always available. This is a better fit than EFI_BLOCK_IO_PROTOCOL for our GPT parsing and BitLocker detection because Block I/O requires that both the read offset (LBA) and the buffer are aligned to the media's IoAlign value. Meeting that constraint forces us to use xmalloc_aligned_pages() with PHYSICAL_ADDRESS_TO_POINTER(), page-granularity allocations, and manual size rounding (ALIGN_TO). Disk I/O handles all of that internally, so callers can use plain xmalloc() or even stack buffers and read exactly the number of bytes they need. Co-developed-by: Claude Opus 4.6 <noreply@anthropic.com>
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