+Marek Vasut too
Hi Heinrich,
On Fri, 9 Aug 2024 at 13:02, Heinrich Schuchardt xypron.glpk@gmx.de wrote:
Am 9. August 2024 20:36:35 MESZ schrieb Simon Glass sjg@chromium.org:
Hi Heinrich,
On Fri, 9 Aug 2024 at 11:32, Heinrich Schuchardt xypron.glpk@gmx.de wrote:
On 01.08.24 19:36, Simon Glass wrote:
The EFI_LOADER_BOUNCE_BUFFER feature was added many years ago. It is not clear whether it is still needed, but 24 boards (lx2160ardb_tfa_stmm, lx2162aqds_tfa_SECURE_BOOT and the like) use it.
This feature uses EFI page allocation to create a 64MB buffer 'in space' without any knowledge of where boards intend to load their images. This may result in image corruption or other problems.
For example, if the feature is enabled on qemu_arm64 it puts the EFI bounce buffer at 1045MB, with the kernel at 1028MB and the ramdisk at 1088MB. The kernel is probably smaller than 27MB but the buffer does overlap the ramdisk.
The solution is probably to use BOUNCE_BUFFER instead, with the EFI version being dropped. For now, show the address of the EFI bounce buffer so people have a better chance to detect the problem.
Note: I avoided converting this #ifdef to use IS_ENABLED() since I hope that the feature may be removed.
EFI_BLOCK_IO_PROTOCOL.ReadBlocks() and EFI_BLOCK_IO_PROTOCOL.WriteBlocks() are expected to block until all bytes are transferred.
The complete file transfer is chunked according to the size of the EFI bounce buffer.
Taking care of alignment issues would best handled by the block uclass.
When CONFIG_BOUNCE_BUFFER=y, bounce_buffer_start_extalign() uses memalign() which limits the bounce buffer to available malloc() memory (typically < 2 MiB).
I cannot see how blk_read() with CONFIG_BOUNCE_BUFFER=y will work if blkcnt * desc->blksz is greater than the available malloc memory.
Yes, it uses malloc(). The maximum read length on MMC, for example, seems to default to 32MB, although it is only 128KB on a few platforms.
I am thinking we should be allocating space in the bloblist to hold all these sorts of things...it can be as large as needed and we can allocate space for it during relocation.
Shouldn't the block uclass support chunking?
It only supports readling whole blocks, if that is what you mean. Are you suggesting changing the blk API, or something else?
It supports reading multiple blocks. If not all blocks fit into the memory that can be assigned via memalgn, the block layer coud separate the blocks into chunks. This would replace the EFI bounce buffer.
Ah OK, yes it could do that.
Regards, Simon