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Subject: RE: pread() and pwrite() system calls
From: Michael Ellerman <michael@ellerman.id.au>
To: David Laight <David.Laight@ACULAB.COM>
Date: Tue, 29 May 2012 18:54:23 +1000
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References: <AE90C24D6B3A694183C094C60CF0A2F6026B6F29@saturn3.aculab.com>
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On Tue, 2012-05-29 at 09:28 +0100, David Laight wrote:
> > > A special pread/pwrite asm stub that just copies
> > > r7 to r0 could be used.
> > > 
> > > Would it be enough to do:
> > > syscall_pread_pwrite:
> > > 	mov 0,7
> > > 	sc
> > > 	blr
> > > and handle the -ve -> errno in C?
> > 
> > Huh? Won't fly, r0 is used for the system call number!
> 
> I was copying that from r7!

Using the non-existant 'mov' instruction!

or 0,7,7

is much clearer :)

cheers