Re: [PATCH v2] Add preadv and pwritev system calls.

From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: Scott Lurndal <scott.lurndal@3leafsystems.com>,
	Matthew Wilcox <matthew@wil.cx>,
	linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	Ulrich Drepper <drepper@redhat.com>
Subject: Re: [PATCH v2] Add preadv and pwritev system calls.
Date: Fri, 12 Dec 2008 20:12:39 +0000	[thread overview]
Message-ID: <20081212201239.GE5774@flint.arm.linux.org.uk> (raw)
In-Reply-To: <4942C1D0.1080009@redhat.com>

On Fri, Dec 12, 2008 at 08:56:00PM +0100, Gerd Hoffmann wrote:
> Russell King wrote:
> >> should be similar to pread/pwrite, e.g:
> >>
> >>     int preadv(fd, iovec, iovec_size, offset)
> > 
> > Yes, and that's easy for glibc to achieve.
> 
> This hints the ABI problem exists at syscall level only.  Is that
> correct?  So we can have
> 
> 	preadv(fd, vec, vlen, off)
> 
> argument ordering at app <-> glibc level and
> 
> 	preadv(fd, vec, off, vlen)
> 
> ordering at glibc <-> kernel (aka syscall) level and it works fine for
> ARM + MIPS + PARISC?

Fine for ARM - and yes, the user visible API should be changed from the
BSD standard.  I don't think anyone in this thread was suggesting that
the user visible argument ordering should be any different from the
original.

Having it in a different order from *BSD at the libc visible interface
is just crazy from the OS portability point of view.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of: