[SeaBIOS] Re: [PATCH 5/6] bios_version: Remove misinterpreted version string

[Carl-Daniel Hailfinger]

Am 17.05.19 um 22:57 schrieb Sam Eiderman:
> From: Liran Alon
>
> This is a workaround for the Windows kernel wrongly extracting
> SystemBiosVersion.
>
> Windows kernel extracts various BIOS information at boot-time.
> The method it use to extract SystemBiosVersion is very hueristic.
> It is done by nt!CmpGetBiosVersion().
>
> nt!CmpGetBiosVersion() works by scanning all BIOS memory
> from 0xF0000 to 0xFFFFF in search for a string of the form x.y
> where x & y are digits. When it finds such a string, it goes
> a bunch of characters backwards until an unknown character is reached,
> checks whether the string contains any of "v 0", "v 1", "Rev ", etc...
> if it does - a match was found. It then continues to find the next
> matches.
>
> In our case, this lead to a debug-print string
> "Intel IGD BDSM enabled at 0x%08x, size %lldMB, dev 00:02.0"
> to be treated as BIOS version (Because of "2.0" at the end, and the
> "v 0" contained in it).
>
> This can be seen by:
>      * Typing "wmic bios get biosversion" in CMD
>      * Reading "HKLM\HARDWARE\DESCRIPTION\System" "SystemBiosVersion"
>
> Therefore, this commit solves the issue by just modifying "00:02.0"
> to "00:02:00".
>
> For reference implementation of nt!CmpGetBiosVersion(), see ReactOS:
> https://doxygen.reactos.org/d5/dd2/i386_2cmhardwr_8c.html
>
> Reviewed-by: Konrad Rzeszutek Wilk 
> Reviewed-by: Arbel Moshe 
> Signed-off-by: Sam Eiderman 
> Signed-off-by: Liran Alon
>
> src/fw/pciinit.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/fw/pciinit.c b/src/fw/pciinit.c
> index c0634bcb..4ab9b724 100644
> --- a/src/fw/pciinit.c
> +++ b/src/fw/pciinit.c
> @@ -328,7 +328,7 @@ static void intel_igd_setup(struct pci_device *dev, void *arg)
>           pci_config_writel(bdf, 0x5C, cpu_to_le32((u32)addr));
>       dprintf(1, "Intel IGD BDSM enabled at 0x%08x, size %lldMB, dev "
>            "00:02.0\n", (u32)addr, bdsm_size >> 20);
>            "00:02:00\n", (u32)addr, bdsm_size >> 20);
> }
> }

This changed notation for a PCI device looks weird, and AFAICS it is
also inconsistent with other places printing PCI device locations.
Replacing "dev " with "device " would fix the issue as well, but people
grepping for "dev " would have a problem.

Regards,
Carl-Daniel