[U-Boot] [BUG] FreeBSD cannot boot with U-Boot patch efi_loader: parameter checks BLOCK_IO_PROTOCOL

Heinrich Schuchardt xypron.glpk at gmx.de
Fri Sep 13 21:48:36 UTC 2019

Hello Emmanuel,

booting current FreeBSD fails since patch
efi_loader: parameter checks BLOCK_IO_PROTOCOL

The reason is that the buffer used by FreeBSD to read is not block aligned.

The UEFI spec requires that EFI_BLOCK_IO_PROTOCOL.ReadBlocks() returns
EFI_INVALID_PARAMETER if the buffer is not properly aligned (i.e. is not
a multiple of EFI_BLOCK_IO_MEDIA.IoAlign)

FreeBSD does not guarantee this alignment, e.g. efi_disk_read_blocks()
is called with buffer 00000000995b08d0 which is not aligned to a
multiple of 512.

FreeBSD function efipart_readwrite writes this error message:
efipart_readwrite: rw=1, blk=62333952 size=1 status=2

The problem can be traced back to the FreeBSD line:

stand/efi/libefi/efipart.c(1043) efipart_realstrategy():
blkbuf = malloc(blkio->Media->BlockSize);

U-Boot does not yet implement the EFI_DISK_IO_PROTOCOL which is a
wrapper for the EFI_BLOCK_IO_PROTOCOL allowing unaligned access.

malloc() could be replaced in FreeBSD by AllocatePages() which returns a
4096 byte aligned memory block.

Best regards


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