Despite the UEFI specification saying "the requirement is that the start address of a buffer must be evenly divisible by IoAlign with no remainder.", it seems that a higher alignment requirement is neecssary on some system (e.g. a Intel NUC system with NVMe SSD). That particular system has IoAlign set to 2, and sometimes returns status 7 when buffers with alignment of 2 are passed. Things seem to work fine with buffers aligned to 4 bytes.
It seems that IoAlign > 1 means 2 ^ IoAlign. There is also such a hint in an example printed in the Driver Writer's Guide: ScsiPassThruMode.IoAlign = 2; // Data must be alligned on 4-byte boundary Pass 2 ^ IoAlign aligned buffers to make sure GRUB2 works properly on all systems. Note: The problem has only noticed with compressed squashfs. It seems that ext4 (and presumably other file system drivers) pass buffers with a higher alignment already. Signed-off-by: Stefan Agner <ste...@agner.ch> --- grub-core/disk/efi/efidisk.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/grub-core/disk/efi/efidisk.c b/grub-core/disk/efi/efidisk.c index f077b5f55..0fc2f0826 100644 --- a/grub-core/disk/efi/efidisk.c +++ b/grub-core/disk/efi/efidisk.c @@ -553,8 +553,16 @@ grub_efidisk_readwrite (struct grub_disk *disk, grub_disk_addr_t sector, d = disk->data; bio = d->block_io; - /* Set alignment to 1 if 0 specified */ - io_align = bio->media->io_align ? bio->media->io_align : 1; + /* + * If IoAlign is > 1, it means alignment by 2^IoAlign + * Note: UEFI spec claims alignment by IoAlign. But there are systems + * with IoAlign=2 which return status 7 if 2 bytes aligned buffers are + * passed. + */ + if (bio->media->io_align > 1) + io_align = 1 << bio->media->io_align; + else + io_align = 1; num_bytes = size << disk->log_sector_size; if ((grub_addr_t) buf & (io_align - 1)) -- 2.36.0 _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
