Re: [Qemu-devel] [PATCH] qtest: add read/write accessors with a specific endianness

[David Gibson <david@gibson.dropbear.id.au>]

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On Thu, Oct 06, 2016 at 05:59:00PM +0200, Laurent Vivier wrote:
> 
> 
> On 06/10/2016 17:41, Peter Maydell wrote:
> > On 6 October 2016 at 16:36, Paolo Bonzini <pbonzini@redhat.com> wrote:
> >>
> >>
> >> On 06/10/2016 16:11, Greg Kurz wrote:
> >>> FWIW, Cedric had another proposal which apparently went unnoticed:
> >>>
> >>> <fc24ad74-da26-a713-9312-a2c2d07fb6a7@kaod.org>
> >>>
> >>> The idea is to add an optional endianness argument to the read*/write*
> >>> commands in the qtest protocol:
> >>> - libqtest then provides explicit _le and _be APIs
> >>> - no extra byteswap is performed on the test program side: qtest
> >>>   actually handles that and does exactly 1 or 0 byteswap.
> >>> - it does not use memread/memwrite
> >>> - the current 'guest native' API where qtest tswaps is preserved
> >>>
> >>
> >> No, this is a worse idea, because the right place to do the swap is in
> >> the "program" (libqtest) not in the "CPU" (QEMU).
> > 
> > Speaking of the right place to do things, perhaps we should
> > reimplement qtest_big_endian() in libqtest.c to send a query
> > to the QEMU-under-test to ask it what TARGET_BIG_ENDIAN says,
> > rather than hardcoding a big list of architectures...
> 
> Yes, it's a good idea.

I disagree.

TARGET_BIG_ENDIAN is simply not well defined - we should avoid using
it at all.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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