Re: CVS commit: src/sys/arch

[Jean-Yves Migeon <jeanyves.migeon%free.fr@localhost>]

On 16.08.2010 22:22, matthew green wrote:
>> Module Name: src
>> Committed By:        jym
>> Date:                Mon Aug 16 19:39:06 UTC 2010
>>
>> Modified Files:
>>      src/sys/arch/i386/i386: machdep.c
>>      src/sys/arch/x86/include: cpu.h
>>
>> Log Message:
>> Add machdep.pae sysctl(7) for i386. Thanks to Paul and Joerg for their
>> reviews.
>>
>> In kernel, it matches the 'i386_use_pae' variable (0: kernel does not use
>> PAE, 1: kernel uses PAE). Will be used by i386 kvm(3) to know the functions
>> that should get called for VA => PA translations.
> 
> does this work for core files as well?
>
> if not, wouldn't this feature be better done use ugly kvm/nlist so
> that it works with the same code on dead kernels?  getting a 0/1
> value via kvm shouldn't really be considered any real problem.

That's the purpose; I don't know of any other way. The sysctl is only
there for practical purposes: cpuctl(8) can indicate that the CPU
supports PAE, but there is no easy way to know if it is active or not
(unless playing with config -x together with the booted kernel, not very
practical...). Hence, the sysctl machdep.

> (why the extern in cpu.h?  i doesn't seem necessary.)

Yes; I wanted to place it at the same level as i386_use_fxsave.
i386_use_pae may get use elsewhere eventually, so I added it to cpu.h.

-- 
Jean-Yves Migeon
jeanyves.migeon%free.fr@localhost