Re: [PATCH] Common compat_sys_sysinfo

[Matthew Wilcox <matthew@wil.cx>]

On Sun, Jan 07, 2007 at 03:13:19PM +0000, Christoph Hellwig wrote:
> and last but not least we probably want a unified mechanisms to deal
> with the 64bit arguments that are broken up into two 32bit ones (not just
> for emulation but also for 32it BE architectures)

It's not BE that is the problem -- drepper thought of that.

What he fundamentally missed was the calling convention where 64-bit
arguments have to be 64-bit aligned, even when they're passed through
registers.  So:

int foo(int, long long);

takes its arguments in arg0, arg2 and arg3, but glibc passes the syscall
arguments in arg0, arg1 and arg2.

I think the Right Way to fix this is for some gcc hacker to implement an
__attribute__((packed_args)) that changes the calling convention for
that function, then we can define asmlinkage to use that on mips and
parisc.

Any budding gcc hackers out there?  ;-)