Date: Tue, 02 Jun 2009 09:42:20 -0700 From: Sam Leffler <sam@freebsd.org> To: Mark Tinguely <tinguely@casselton.net> Cc: freebsd-arm@freebsd.org Subject: Re: cache corruption patch Message-ID: <4A25566C.7020806@freebsd.org> In-Reply-To: <200905282320.n4SNK87M043401@casselton.net> References: <200905282320.n4SNK87M043401@casselton.net>
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Mark Tinguely wrote: > There has been several occurrences of memory corruption in ARM due to caching > issues. A couple recent examples are problems with the SATA drive and new USB > code. > > This patch tracks kernel mapped pages and detects when they are shared > with existing user mapped pages and other kernel mapped pages. This patch > has gone through some refinement in the last couple days with feed back > from testers and is getting ready for being committed before the FreeBSD 8.0 > freeze. > > This patch should allow the removal of added cache invalidation commands to > the dma. > > The patch is located at: > > http://www.casselton.net/~tinguely/arm_pmap_unmanaged.diff > > For those interested, I can give a long explanation of the patch. > Have you measured the overhead of this additional state tracking (time+space)? It appears to affect only dma buffers. Not sure what "added cache invalidation commands" you're referring to, can you explain? Perhaps you could just provide a separate patch that shows which bus_dma ops you think can go away. Sam
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