[PATCH] Fix MIPS N64 build.

[Waldemar Brodkorb]

Hi Steve,
Steve Ellcey wrote,

> On Sat, 2014-02-15 at 11:14 +0100, Bernhard Reutner-Fischer wrote:
> > On Fri, Feb 14, 2014 at 03:21:32PM +0100, Waldemar Brodkorb wrote:
> 
> > > Works for me, too.
> > > Did you start any real machine or emulator with this? I get bus
> > > errors after executing any application.
> > 
> > I suspect this needs a different register passing handling
> > (__LONG_LONG_PAIR) then.
> 
> Waldemar,  I did run a pread/pwrite test case compiled with "-mips64r2
> -mabi=n32" on both big-endian and a little-endian systems.  I did not
> get a bus error in either case when calling pread or pwrite.  I also
> tried calling pread64 and pwrite64 instead but those worked as well.  Do
> you have a small test case that fails for you that you could send me?
> 
> I think the Bernhard's comment about __LONG_LONG_PAIR is correct and
> my best guess as to the fix would be to change all of the
> 
> 		__syscall_pwrite(fd, buf, count, offset)
> 
> lines in libc/sysdeps/linux/mips/pread_write.c to be:
> 
> 		__syscall_pwrite(fd, buf, count, __LONG_LONG_PAIR ((long) (offset >> 31), (long) offset))
> 
> but I was hoping to reproduce the error first, then try this fix. Since
> the current code works for me I am not sure how to test this change.
> 
> Note that when testing this I did use my current patch of changing
> __NR_pread and __NR_write to __NR_pread64 and __NR_write64.

Oh I am so sorry. I made it unclear. The bus errors and segfaults I
get while booting a linux MIPS64 N32 system in qemu are not related to
this patch. I was just wondering if you also get problems when using
a complete linux system with MIPS64 N32. I am still investigating.

best regards
        Waldemar