[coreboot] [LinuxBIOS] Intel microcode revision code

[Carl-Daniel Hailfinger]

On 20.02.2008 18:52, Stefan Reinauer wrote:
> Carl-Daniel Hailfinger wrote:
>> On 20.02.2008 17:19, Stefan Reinauer wrote:
>>  
>>> * ron minnich <rminnich at gmail.com> [071212 17:19]:
>>>      
>>>>> Question to you guys: why is the first wrmsr instruction there? 
>>>>> From my
>>>>> understanding, by not properly initialising ECX, EAX and EDX this 
>>>>> will
>>>>> overwrite whatever is in the MSR pointed to by ECX?!
>>>>>
>>>>> BTW I tried out your code on our target hardware (Intel Celeron M, 
>>>>> 600 MHz)
>>>>> and with that first wrmsr line in place it hangs and without it, 
>>>>> it runs
>>>>> just fine.
>>>>>               
>>>> Thanks Martin. That looks like quite a nice bug catch you've done :-)
>>>>           
>>> Here's a patch that resolves the issue.
>>>
>>> Signed-off-by: Stefan Reinauer <stepan at coresystems.de>
>>>
>>> Index: src/cpu/intel/microcode/microcode.c
>>> ===================================================================
>>> --- src/cpu/intel/microcode/microcode.c    (revision 3111)
>>> +++ src/cpu/intel/microcode/microcode.c    (working copy)
>>> @@ -33,7 +33,6 @@
>>>       */
>>>      msr_t msr;
>>>      __asm__ volatile (
>>> -        "wrmsr\n\t"
>>>       
>>
>> ACK.
>>
>>  
>>>          "xorl %%eax, %%eax\n\t"
>>>          "xorl %%edx, %%edx\n\t"
>>>          "movl $0x8b, %%ecx\n\t"
>>> @@ -60,7 +59,7 @@
>>>      char *c;
>>>      msr_t msr;
>>>     
>>> -    /* cpuid sets msr 0x8B iff a microcode update has been loaded. */
>>> +    /* cpuid sets msr 0x8B if a microcode update has been loaded. */
>>>       
>>
>> NACK. "IFF" is shorthand for "if and only if", see 
>> http://en.wikipedia.org/wiki/If_and_only_if
>>   
>
> That's silly. This is not a mathematical expression nor a 
> philosophical disquisition but a sentence. I am not even convinced 
> that it was meant that way rather than being just a typo. If you have 
> reasons to assume it means "If and only if" then let's write it that way.

Merriam-Webster agrees with me that "iff" is a word: 
http://www.merriam-webster.com/dictionary/iff
So this is a valid sentence and I see no reason to change it. Unless the 
bit can be set even of no microcode update has been uploaded, "iff" is 
the only correct word.

Regards,
Carl-Daniel

-- 
http://www.hailfinger.org/