Date: Sat, 24 Jan 2015 07:56:37 -0700 From: Ian Lepore <ian@freebsd.org> To: Konstantin Belousov <kib@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r277643 - in head/sys: arm/arm dev/mem i386/i386 mips/mips sparc64/sparc64 Message-ID: <1422111397.1038.53.camel@freebsd.org> In-Reply-To: <201501241251.t0OCpGa8053192@svn.freebsd.org> References: <201501241251.t0OCpGa8053192@svn.freebsd.org>
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On Sat, 2015-01-24 at 12:51 +0000, Konstantin Belousov wrote: > Author: kib > Date: Sat Jan 24 12:51:15 2015 > New Revision: 277643 > URL: https://svnweb.freebsd.org/changeset/base/277643 > > Log: > Remove Giant from /dev/mem and /dev/kmem. It is definitely not needed > for i386, and from the code inspection, nothing in the > arm/mips/sparc64 implementations depends on it. > I'm not sure I agree with that. On arm the memrw() implementation uses a single statically-allocated page of kva space into which it maps each physical page in turn in the main loop. What prevents preemption or multicore access to /dev/mem from trying to use that single page for multiple operations at once? -- Ian
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