Re: Mach-O binary format support and Darwin syscall personality [Was: uts banner changes]

[Kyle Moffett <mrmacman_g4@mac.com>]

On Dec 12, 2006, at 13:20:19, Linus Torvalds wrote:
> That said, powerpc simply doesn't historically do any system call  
> translation, so you'll just have to implement the same kind of  
> translation layer that sparc has done, for example.

Thanks a lot for all your help.  I've got two last questions:  From  
the code in entry_32.s I can dig up "current" from ((struct  
paca_struct *)r13)->__current to read a personality flag from it,  
right?  Digging up offsets in assembly can't be very fun :-\   
Secondly, is there a preferred existing field into which I should  
stick said flag or just stuff it somewhere?

This part seems like the easiest so far; no icky binary format  
parsing, no confusing memory maps.  Thanks once again!

>> So I guess all I have to do is:
>>  (A)  Write a bunch of new syscall handlers taking arguments of  
>> the same types
>> as the Darwin syscall handlers,
>
> Yes. The big issue tends to be to translate all the errno's and the  
> fcntl structure pointers etc. THAT can be quite painful indeed. You  
> might ask David Miller and company about their SunOS stuff, and  
> look at things like
>
> 	arch/sparc/kernel/{sys_sunos.c,sunos_ioctl.c}
>
> for some sorry examples.

Ok, I figured it was going to be ugly; maybe not quite _that_ ugly  
but my hopes weren't high enough for you to dash to any real degree :-D.

Cheers,
Kyle Moffett