Date: Thu, 15 Sep 2005 13:15:01 -0600 From: Scott Long <scottl@samsco.org> To: John Baldwin <jhb@FreeBSD.org> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/alpha/alpha busdma_machdep.c Message-ID: <4329C835.6020104@samsco.org> In-Reply-To: <200509151341.42862.jhb@FreeBSD.org> References: <200509151709.j8FH9hkm099887@repoman.freebsd.org> <200509151341.42862.jhb@FreeBSD.org>
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John Baldwin wrote: > On Thursday 15 September 2005 01:09 pm, John Baldwin wrote: > >>jhb 2005-09-15 17:09:42 UTC >> >> FreeBSD src repository >> >> Modified files: >> sys/alpha/alpha busdma_machdep.c >> Log: >> Add a memory barrier for PREWRITE operations to ensure all writes by the >> CPU have drained before further writes to kick off the operation. > > > Other architectures with relaxed memory ordering probably also need thus such > as ia64, powerpc, and perhaps amd64. sparc64 already has a barrier. BTW, it > seems that the bus_dma code could be somewhat simplified if there was a > sys/kern/subr_busdma.c that contained routines to implement bounce buffers > that could be used by the MD code since the MD code that does do bounce pages > tends to duplicate a lot of stuff between the different archs. > Indeed it does, and if you want to work on it, please feel free to send it to me for review. Scott
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