linux emulation: Preliminary support for more auxvec's [patch]

[Marcin Cieslak]

Kostik Belousov wrote:

> Do you know of any situation where we _must_ have those new auxvec you
> implemented ?

No, I learned about them today when I analyzed my auxvec fingerprint 
from the real amd64 and i386 Linux boxes.
> 
>>
>> http://akson.sgh.waw.pl/~saper/FreeBSD/linux/auxvec.diff
> I only briefly looked over it.
> 
> I suggest that the new AT_COUNT requires more thinking. Look at the
> src/libexec/rtld-elf/rtld.c, _rtld(), at line 338, where the auxvec is
> digested by FreeBSD dynamic linker. It seems to be harmless, but at
> least this is inconsistent. May be, AT_LINUX_PLATFORM etc defines
> would make more sense.

machine/elf.h will get updated with installworld (or make install in 
includes) and rtld should get be recompiled with this.

I did this and it works fine as it worked. The impact of this is 
limited, since all the auxvec's rtld need are stored early.
I don't think the AT_COUNT things is correct.

> 
> Do you actually need imgp->machine member ? It seems that it is used
> only inside linux_copyout_strings ?

No, it's referenced in elf_linux_fixup - that's the reason I need it.

>> This was made against 7-STABLE, but there no major differences in 
>> -current. It is also trivial to port to 64-bit amd64 emulation.
> Hmm, what are you referencing there ? I know only about one mostly
> stalled effort.

Well, anyway the logic is pretty platform-independent and one needs to 
be careful about pointer sizes (AT_PLATFORM) and such.

Newly introduced linux_get_machine should take care of the 64-bit case.
If we are going to support dynamic switching between 32 and 64 bit code 
this will need to be dynamic as well ("x86_64" vs "i686").

I have my doubts about the linux_times() function in linux_misc.c,
it tries to convert the clock tick to the FreeBSD value. Maybe it's no 
longer necessary.

If this is a problem, we can hardcode value "100" as being returned.

--Marcin

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