cvs commit: src/sys/boot/i386/libi386 biossmap.c

John Baldwin jhb at
Sat Jun 7 03:26:09 UTC 2008

On Friday 06 June 2008 11:07:32 pm John Baldwin wrote:
> jhb         2008-06-07 03:07:32 UTC
>   FreeBSD src repository
>   Modified files:
>     sys/boot/i386/libi386 biossmap.c 
>   Log:
>   SVN rev 179631 on 2008-06-07 03:07:32Z by jhb
>   Workaround a bug in the BIOS of Dell R900 machines.  Specifically, each
>   entry in the SMAP is a 20 byte structure and they are queried from the
>   BIOS via sucessive BIOS calls.  Due to an apparent bug in the R900's
>   BIOS, for some SMAP requests the BIOS overflows the 20 byte buffer
>   trashing a few bytes of memory immediately after the SMAP structure.  As
>   a workaround, add 8 bytes of padding after the SMAP structure used in
>   the loader for SMAP queries.
>   PR:             i386/122668
>   Submitted by:   Mike Hibler  mike, silby
>   MFC after:      3 days

The code to parse the SMAP in the kernel from vm86 mode is unaffected as it 
allocates an entire page for use when fetching the SMAP entry.

John Baldwin

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