From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Scott Wood <scottwood@freescale.com>
Cc: Stefan Weil <sw@weilnetz.de>,
qemu-ppc@nongnu.org, Alexander Graf <agraf@suse.de>,
QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/2] tcg/ppc*: Move cache initialization to ppc specific code
Date: Tue, 04 Oct 2011 08:06:42 +0200 [thread overview]
Message-ID: <1317708402.29415.215.camel@pasglop> (raw)
In-Reply-To: <4E8A2E77.5000309@freescale.com>
> Not doing it sometimes invokes crash penalties for us. :-)
>
> We could add some way to skip the invalidation if we know the host is an
> implementation that doesn't need it, possibly depending on the context
> (is it just DMA he wants to avoid doing this on[1], or do their chips
> have a fully coherent icache?), but IMHO functional correctness should
> come first.
>
> -Scott
>
> [1] In which case we need to figure out how to tell at that point
> whether it was DMA, preferably by something less hackish than saying,
> "This function is used for DMA and breakpoints. Breakpoints are 4
> bytes, and flushing on a 4-byte DMA isn't as painful as larger DMAs."
AT_HWCAP will tell you, look for PPC_FEATURE_ICACHE_SNOOP, in this case
all you need is sync, one icbi, isync (the arch documents the sequence
iirc).
Cheers,
Ben.
next prev parent reply other threads:[~2011-10-04 6:07 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-03 20:43 [Qemu-devel] Clean cache related code which was used only by PPC hosts Stefan Weil
2011-10-03 20:43 ` [Qemu-devel] [PATCH 1/2] linux-user: Remove unused code Stefan Weil
2011-10-03 21:12 ` [Qemu-trivial] " Stefan Weil
2011-10-03 21:12 ` Stefan Weil
2011-10-04 7:56 ` Peter Maydell
2011-10-05 8:26 ` Stefan Hajnoczi
2011-10-03 20:43 ` [Qemu-devel] [PATCH 2/2] tcg/ppc*: Move cache initialization to ppc specific code Stefan Weil
2011-10-03 20:52 ` [Qemu-devel] [Qemu-ppc] " Scott Wood
2011-10-03 21:10 ` Stefan Weil
2011-10-03 21:36 ` Alexander Graf
2011-10-03 21:50 ` Scott Wood
2011-10-03 22:06 ` Alexander Graf
2011-10-03 22:07 ` Scott Wood
2011-10-03 22:11 ` Alexander Graf
2011-10-03 21:40 ` Scott Wood
2011-10-03 21:43 ` Alexander Graf
2011-10-03 21:51 ` Scott Wood
2011-10-03 22:03 ` Alexander Graf
2011-10-04 6:06 ` Benjamin Herrenschmidt [this message]
2011-10-04 5:55 ` Stefan Weil
2011-10-04 6:29 ` Paolo Bonzini
2011-10-04 8:11 ` Peter Maydell
2011-10-04 15:44 ` Scott Wood
2011-10-03 23:12 ` [Qemu-devel] " malc
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