From: Paul Mackerras <paulus@samba.org>
To: Alexander Graf <agraf@suse.de>
Cc: "Cédric Le Goater" <clg@fr.ibm.com>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"kvm@vger.kernel.org mailing list" <kvm@vger.kernel.org>
Subject: Re: [PATCH v2 3/3] KVM: PPC: Book3S: MMIO emulation support for little endian guests
Date: Wed, 9 Oct 2013 16:59:20 +1100 [thread overview]
Message-ID: <20131009055920.GA10650@drongo> (raw)
In-Reply-To: <5F0A1154-D417-454C-A3CD-59AEF7EF0D97@suse.de>
On Wed, Oct 09, 2013 at 01:46:29AM +0200, Alexander Graf wrote:
>
>
> Am 09.10.2013 um 01:31 schrieb Paul Mackerras <paulus@samba.org>:
>
> > True, until we get to POWER8 with its split little-endian support,
> > where instructions and data can have different endianness...
>
> How exactly does that work?
They added an extra MSR bit called SLE which enables the split-endian
mode. It's bit 5 (IBM numbering). For backwards compatibility, the
LE bit controls instruction endianness, and data endianness depends on
LE ^ SLE, that is, with SLE = 0 things work as before. With SLE=1 and
LE=0 you get little-endian data and big-endian instructions, and vice
versa with SLE=1 and LE=1.
There is also a user accessible "mtsle" instruction that sets the
value of the SLE bit. This enables programs to flip their data
endianness back and forth quickly, so it's usable for short
instruction sequences, without the need to generate instructions of
the opposite endianness.
Paul.
next prev parent reply other threads:[~2013-10-09 5:59 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-08 14:12 [PATCH v2 0/3] KVM: PPC: Book3S: MMIO support for Little Endian guests Cédric Le Goater
2013-10-08 14:12 ` [PATCH v2 1/3] KVM: PPC: Book3S: add helper routine to load guest instructions Cédric Le Goater
2013-10-08 14:12 ` [PATCH v2 2/3] KVM: PPC: Book3S: add helper routines to detect endian Cédric Le Goater
2013-10-08 14:12 ` [PATCH v2 3/3] KVM: PPC: Book3S: MMIO emulation support for little endian guests Cédric Le Goater
2013-10-08 14:25 ` Alexander Graf
2013-10-08 15:07 ` Cedric Le Goater
2013-10-08 15:31 ` [PATCH v3 " Cédric Le Goater
2013-10-08 15:36 ` Alexander Graf
2013-10-08 16:10 ` Cedric Le Goater
2013-10-08 16:43 ` [PATCH v4 0/3] KVM: PPC: Book3S: MMIO support for Little Endian guests Cédric Le Goater
2013-10-08 16:43 ` [PATCH v4 1/3] KVM: PPC: Book3S: add helper routine to load guest instructions Cédric Le Goater
2013-10-08 16:43 ` [PATCH v4 2/3] KVM: PPC: Book3S: add helper routines to detect endian order Cédric Le Goater
2013-10-08 16:43 ` [PATCH v4 3/3] KVM: PPC: Book3S: MMIO emulation support for little endian guests Cédric Le Goater
2013-10-08 23:31 ` [PATCH v2 " Paul Mackerras
2013-10-08 23:46 ` Alexander Graf
2013-10-09 5:59 ` Paul Mackerras [this message]
2013-10-09 8:29 ` Alexander Graf
2013-10-09 8:42 ` Cedric Le Goater
2013-10-10 10:16 ` Paul Mackerras
2013-11-04 11:44 ` Alexander Graf
2013-11-05 12:28 ` Cedric Le Goater
2013-11-05 13:01 ` Alexander Graf
2013-11-05 17:22 ` [PATCH v5 0/6] KVM: PPC: Book3S: MMIO support for Little Endian guests Cédric Le Goater
2013-11-05 17:22 ` [PATCH v5 1/6] KVM: PPC: Book3S: add helper routine to load guest instructions Cédric Le Goater
2013-11-05 17:22 ` [PATCH v5 2/6] KVM: PPC: Book3S: add helper routines to detect endian Cédric Le Goater
2014-01-02 20:05 ` Alexander Graf
2014-01-08 17:22 ` Cedric Le Goater
2013-11-05 17:22 ` [PATCH v5 3/6] KVM: PPC: Book3S: MMIO emulation support for little endian guests Cédric Le Goater
2014-01-02 20:22 ` Alexander Graf
2014-01-08 17:23 ` Cedric Le Goater
2014-01-08 17:34 ` Alexander Graf
2014-01-08 17:40 ` Cedric Le Goater
2014-01-08 17:35 ` [PATCH v6] " Cédric Le Goater
2014-01-09 10:02 ` [PATCH v7] " Cédric Le Goater
2014-01-09 10:17 ` Alexander Graf
2014-01-09 10:33 ` Cedric Le Goater
2014-01-09 10:51 ` [PATCH v8] " Cédric Le Goater
2014-01-09 10:55 ` Alexander Graf
2013-11-05 17:22 ` [PATCH v5 4/6] KVM: PPC: Book3S: modify kvmppc_need_byteswap() for little endian host Cédric Le Goater
2013-11-08 14:36 ` [PATCH v5.1 " Cedric Le Goater
2014-01-02 20:28 ` Alexander Graf
2014-01-02 20:25 ` [PATCH v5 " Alexander Graf
2013-11-05 17:22 ` [PATCH v5 5/6] powerpc: add Split Little Endian bit to MSR Cédric Le Goater
2013-11-05 17:22 ` [PATCH v5 6/6] KVM: PPC: Book3S: modify byte loading when guest uses Split Little Endian Cédric Le Goater
2014-01-02 20:26 ` Alexander Graf
2013-11-06 5:55 ` [PATCH v2 3/3] KVM: PPC: Book3S: MMIO emulation support for little endian guests Paul Mackerras
2013-11-08 14:29 ` Cedric Le Goater
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