Date: Tue, 4 Aug 2015 18:54:11 -0500 From: Jason Harmening <jason.harmening@gmail.com> To: "Bjoern A. Zeeb" <bz@FreeBSD.org>, "Jason A. Harmening" <jah@FreeBSD.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r286296 - in head/sys: amd64/amd64 arm/arm arm/include arm64/arm64 i386/i386 i386/include mips/mips powerpc/aim powerpc/booke powerpc/include powerpc/powerpc sparc64/include sparc64/spa... Message-ID: <55C150A3.4030509@gmail.com> In-Reply-To: <C80D87EE-2429-4FD8-8738-F6EF722A7FC4@FreeBSD.org> References: <201508041946.t74JkExD070238@repo.freebsd.org> <C80D87EE-2429-4FD8-8738-F6EF722A7FC4@FreeBSD.org>
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On 08/04/15 18:22, Bjoern A. Zeeb wrote: > >> On 04 Aug 2015, at 19:46 , Jason A. Harmening <jah@FreeBSD.org> wrote: >> >> Author: jah >> Date: Tue Aug 4 19:46:13 2015 >> New Revision: 286296 >> URL: https://svnweb.freebsd.org/changeset/base/286296 >> >> Log: >> Add two new pmap functions: >> vm_offset_t pmap_quick_enter_page(vm_page_t m) >> void pmap_quick_remove_page(vm_offset_t kva) >> >> These will create and destroy a temporary, CPU-local KVA mapping of a specified page. >> >> Guarantees: >> --Will not sleep and will not fail. >> --Safe to call under a non-sleepable lock or from an ithread >> >> Restrictions: >> --Not guaranteed to be safe to call from an interrupt filter or under a spin mutex on all platforms >> --Current implementation does not guarantee more than one page of mapping space across all platforms. MI code should not make nested calls to pmap_quick_enter_page. >> --MI code should not perform locking while holding onto a mapping created by pmap_quick_enter_page >> >> The idea is to use this in busdma, for bounce buffer copies as well as virtually-indexed cache maintenance on mips and arm. >> >> NOTE: the non-i386, non-amd64 implementations of these functions still need review and testing. > > Most of this description should go into a section 9 man page rather than the commit message ;-) > > /bz > Yep, I'm planning to write one.
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