[LinuxBIOS] [PATCH] rewrite generic x86 CAR code

[Marc Jones]

Carl-Daniel Hailfinger wrote:
> Marc?
> 
> While the patch is against the generic x86 CAR code, it can also be
> easily modified to work with AMD K8/K9/K10 CAR code. Especially the
> recent K10 commit made AMD CAR an #ifdef mess which could be sorted out
> nicely.
> 
Yes, It would be good to clean them all up.



> This patch is part of my quest to clean up those v2 code parts which
> will someday end up in v3.
A good cause :)

>>  
>> -#if CacheSize == 0x10000 
>> -        /* enable caching for 64K using fixed mtrr */
>> +/* 0x06 is the WB IO type for a given 4k segment.
>> + * segs is the number of 4k segments we want to use for CAR.
>> + * subpart is the nth 32-bit window into IO type configuration.
>> + * reg is the register where the IO type should be stored.
>> + */
>> +.macro extractmask segs, subpart, reg
>> +.if \segs - (\subpart * 4) <= 0
>> +	xorl \reg, \reg
>> +.elseif \segs - (\subpart * 4) == 1
>> +	movl $0x06000000, \reg
>> +.elseif \segs - (\subpart * 4) == 2
>> +	movl $0x06060000, \reg
>> +.elseif \segs - (\subpart * 4) == 3
>> +	movl $0x06060600, \reg
>> +.elseif \segs - (\subpart * 4) >= 4
>> +	movl $0x06060606, \reg
>> +.endif
>> +.endm

Why not just pass in the number of 4k pieces, \segs - (\subpart * 4)?


>> +.macro simplemask_helper segs, subpart
>> +.if \subpart & 0x1
>> +	extractmask \segs, \subpart, %eax
>> +.else
>> +	extractmask \segs, \subpart, %edx
>> +.endif
>> +.endm
>> +/* size is the cache size in bytes we want to use for CAR.
>> + * part is the nth 64-bit window into IO type configuration.
>> + */
>> +.macro simplemask size, part
>> +	simplemask_helper (\size / 0x1000), (\part * 2 + 1)
>> +	simplemask_helper (\size / 0x1000), (\part * 2)
>> +.endm
>> +

The \part stuff isn't really intuitive. I think an .if size > 32K would 
be better and then the caller doesn't have to know \part. Building on 
that the macro could fill in ecx as well.

What do you think?

Marc



-- 
Marc Jones
Senior Firmware Engineer
(970) 226-9684 Office
mailto:Marc.Jones at amd.com
http://www.amd.com/embeddedprocessors