Date: Tue, 28 Feb 2012 19:42:40 +0000 (UTC) From: Ed Maste <emaste@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r232267 - head/sys/x86/x86 Message-ID: <201202281942.q1SJgeed084974@svn.freebsd.org>
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Author: emaste Date: Tue Feb 28 19:42:40 2012 New Revision: 232267 URL: http://svn.freebsd.org/changeset/base/232267 Log: Workaround for PCIe 4GB boundary issue Enforce a boundary of no more than 4GB - transfers crossing a 4GB boundary can lead to data corruption due to PCIe limitations. This change is a less-intrusive workaround that can be quickly merged back to older branches; a cleaner implementation will arrive in HEAD later but may require KPI changes. This change is based on a suggestion by jhb@. Reviewed by: scottl, jhb Sponsored by: Sandvine Incorporated MFC after: 3 days Modified: head/sys/x86/x86/busdma_machdep.c Modified: head/sys/x86/x86/busdma_machdep.c ============================================================================== --- head/sys/x86/x86/busdma_machdep.c Tue Feb 28 19:39:54 2012 (r232266) +++ head/sys/x86/x86/busdma_machdep.c Tue Feb 28 19:42:40 2012 (r232267) @@ -227,6 +227,14 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_dma_tag_t newtag; int error = 0; + /* Always enforce at least a 4GB (2GB for PAE) boundary. */ +#if defined(__amd64__) + if (boundary == 0 || boundary > ((bus_addr_t)1 << 32)) + boundary = (bus_size_t)1 << 32; +#elif defined(PAE) + if (boundary == 0 || boundary > ((bus_addr_t)1 << 31)) + boundary = (bus_size_t)1 << 31; +#endif /* Basic sanity checking */ if (boundary != 0 && boundary < maxsegsz) maxsegsz = boundary;
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