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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alexander Graf <agraf@suse.de>
Cc: "qemu-ppc@nongnu.org list:PowerPC" <qemu-ppc@nongnu.org>,
	"qemu-devel@nongnu.org qemu-devel" <qemu-devel@nongnu.org>,
	Richard Henderson <rth@twiddle.net>
Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 16/16] target-ppc: Convert to new ldst opcodes
Date: Thu, 05 Sep 2013 21:40:55 +1000	[thread overview]
Message-ID: <1378381255.4321.155.camel@pasglop> (raw)
In-Reply-To: <DE81906E-29DB-454C-8F0D-743A3100EF5D@suse.de>

On Thu, 2013-09-05 at 11:08 +0200, Alexander Graf wrote:
> On 04.09.2013, at 23:05, Richard Henderson wrote:
> 
> > This lets us change "le_mode" to "end_mode" and fold away nearly all
> > of the tests for the current cpu endianness, and removing all of the
> > explicitly generated bswap opcodes.

Only nit: I find "end_mode" a very confusing identifier :-) "end"
usually means something else ! Why not endian_mode ?
> > 
> > Cc: qemu-ppc@nongnu.org
> > Signed-off-by: Richard Henderson <rth@twiddle.net>
> 
> No complaints from me, apart from the usual "LE mode isn't necessarily what you think it is on PPC" one. But the code would be as broken as before IIUC.
> 
> Ben, you had some insight in how LE mode on different PPC flavors work. Could you please make sure we're not walking into the wrong direction here?

I haven't seen the patch itself for some reason (and I'm about to go off
for a few days). The early day powerpc endian mode can be safely ignored
I think, I don't even remember the details myself, I think it induced
some changes to the byte lanes ordering on the bus and thus required the
host bridge to be adjusted.

The embedded PPCs have simply a per-page E bit in the TLB controlling
the endianness of accesses through the translation, the endianness is
"clean" in that case, and the bus doesn't flip around so it's akin to
what P7 does but with a finer granularity.

Cheers,
Ben.

  reply	other threads:[~2013-09-05 11:41 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-04 21:04 [Qemu-devel] [PATCH 00/16] Streamlining endian handling in TCG Richard Henderson
2013-09-04 21:04 ` [Qemu-devel] [PATCH 01/16] tcg: Add TCGMemOp Richard Henderson
2013-09-04 21:04 ` [Qemu-devel] [PATCH 02/16] tcg-i386: Use TCGMemOp within qemu_ldst routines Richard Henderson
2013-09-04 21:04 ` [Qemu-devel] [PATCH 03/16] tcg-aarch64: " Richard Henderson
2013-09-04 21:04 ` [Qemu-devel] [PATCH 04/16] tcg-arm: " Richard Henderson
2013-09-04 21:04 ` [Qemu-devel] [PATCH 05/16] tcg-s390: " Richard Henderson
2013-09-04 21:04 ` [Qemu-devel] [PATCH 06/16] tcg-ppc: " Richard Henderson
2013-09-04 21:04 ` [Qemu-devel] [PATCH 07/16] tcg-ppc64: " Richard Henderson
2013-09-04 21:04 ` [Qemu-devel] [PATCH 08/16] tcg-hppa: " Richard Henderson
2013-09-04 21:04 ` [Qemu-devel] [PATCH 09/16] tcg-mips: " Richard Henderson
2013-09-04 21:04 ` [Qemu-devel] [PATCH 10/16] tcg-sparc: " Richard Henderson
2013-09-04 21:05 ` [Qemu-devel] [PATCH 11/16] tcg: Add qemu_ld_st_i32/64 Richard Henderson
2013-09-04 21:05 ` [Qemu-devel] [PATCH 12/16] exec: Add both big- and little-endian memory helpers Richard Henderson
2013-09-04 21:05 ` [Qemu-devel] [PATCH 13/16] tcg-i386: Tidy softmmu routines Richard Henderson
2013-09-04 21:05 ` [Qemu-devel] [PATCH 14/16] tcg-i386: Remove "cb" output restriction from qemu_st8 for i386 Richard Henderson
2013-09-04 21:05 ` [Qemu-devel] [PATCH 15/16] tcg-i386: Support new ldst opcodes Richard Henderson
2013-09-04 21:05 ` [Qemu-devel] [PATCH 16/16] target-ppc: Convert to " Richard Henderson
2013-09-05  9:08   ` [Qemu-devel] [Qemu-ppc] " Alexander Graf
2013-09-05 11:40     ` Benjamin Herrenschmidt [this message]
2013-09-05 12:59       ` Alexander Graf
2013-09-05 13:37         ` Benjamin Herrenschmidt
2013-09-05 15:35       ` Richard Henderson

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