Re: ELF TLS ABI vs L4 ABI

[Marcus Brinkmann]

At Thu, 18 Nov 2004 13:26:18 +0100,
Marcus Brinkmann wrote:
> * Some system call stubs need to access the UTCB in user space.  For
>   these, I'd like to have different user space stubs which instead
>   take the UTCB address as an argument in a free register and can be
>   used by the ELF version of libl4.  In fact, one could even have
>   those stubs access the UTCB in the ELF TLS directly, if one wants to
>   (but then they should definitely not be in the KIP, but maintained
>   in glibc).  The ELF version of libl4 would then access those stubs
>   instead of the official ones.

Well, this was silly.  We can just declare that the UTCB needs to be
passed in the register that the L4 ABI specifies for that anyway.  So
the ELFish libl4 can restore the UTCB in that register before the
system call, and reload the thread pointer afterwards.

Thanks,
Marcus