Date: Mon, 24 Nov 2003 13:19:35 +0000
From: Jamie Lokier <jamie@shareable.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: transmeta cpu code question
Message-ID: <20031124131934.GA30489@mail.shareable.org>
References: <20031120020218.GJ3748@schottelius.org> <20031120232532.GA8229@mail.shareable.org> <200311210834.hAL8YOKw000394@81-2-122-30.bradfords.org.uk> <20031121084857.GA10343@mail.shareable.org> <bps9vu$osu$1@cesium.transmeta.com>
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H. Peter Anvin wrote:
> If there is something that one could imagine doing at the CMS level to
> help on Linux, it would probably be something like making it optional
> to actually perform stores beneath the stack pointer, in which case a
> lot of stack frame operations could be done purely in registers.  CMS
> will do them in registers already, but will be forced to perform a
> store at the end of the translation anyway in order to keep exact x86
> semantics.

You couldn't enable that globally, because it'd break userspace
programs which write below the stack safely using sigaltstack(), or
which even use the stack pointer as a general purpose register (I've
coded games which do that in tight rendering loops), or during funky
thunking code.

It sounds like a good thing to add as a per-task feature though.

-- Jamie
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