Am 06.02.2023 um 16:54 hat Cédric Le Goater geschrieben:
> On 1/20/23 13:25, Kevin Wolf wrote:
> > From: Xiang Zheng <zhengxia...@huawei.com>
> >
> > Currently we fill the VIRT_FLASH memory space with two 64MB NOR images
> > when using persistent UEFI variables on virt board. Actually we only use
> > a very small(non-zero) part of the memory while the rest significant
> > large(zero) part of memory is wasted.
> >
> > So this patch checks the block status and only writes the non-zero part
> > into memory. This requires pflash devices to use sparse files for
> > backends.
> >
> > Signed-off-by: Xiang Zheng <zhengxia...@huawei.com>
> >
> > [ kraxel: rebased to latest master ]
> >
> > Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
> > Message-Id: <20221220084246.1984871-1-kra...@redhat.com>
> > Reviewed-by: Daniel P. Berrangé <berra...@redhat.com>
> > Reviewed-by: Kevin Wolf <kw...@redhat.com>
> > Signed-off-by: Kevin Wolf <kw...@redhat.com>
>
> This newly merged patch introduces a "regression" when booting an Aspeed
> machine. The following extra m25p80 patch (not yet merged) is required
> for the issue to show:
>
> https://lore.kernel.org/qemu-devel/20221115151000.2080833-1-...@kaod.org/
>
> U-Boot fails to find the filesystem in that case.
>
> It can be easily reproduced with the witherspoon-bmc machine and seems
> to be related to the use of a UBI filesystem. Other Aspeed machines not
> using UBI are not impacted.
>
> Here is a tentative fix. I don't know enough the block layer to explain
> what is happening :/
I was puzzled for a moment, but...
> @@ -39,7 +39,7 @@ static int blk_pread_nonzeroes(BlockBack
> return ret;
> }
> if (!(ret & BDRV_BLOCK_ZERO)) {
> - ret = bdrv_pread(bs->file, offset, bytes,
'bs->file' rather than 'bs' really looks wrong. I think replacing that
would already fix the bug you're seeing.
Just to be sure, how did you configure the block backend? bs->file would
happen to work more or less with raw over file-posix (which is probably
what Gerd tested), but I think it breaks with anything else.
> + ret = blk_pread(blk, offset, bytes,
> (uint8_t *) buf + offset, 0);
blk_*() makes even more sense conceptually, but it should behave the
same.
Kevin
