Date: Tue, 13 Oct 2015 23:43:06 +0000 (UTC) From: "Conrad E. Meyer" <cem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r289274 - head/sys/dev/ntb/ntb_hw Message-ID: <201510132343.t9DNh63e015180@repo.freebsd.org>
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Author: cem Date: Tue Oct 13 23:43:06 2015 New Revision: 289274 URL: https://svnweb.freebsd.org/changeset/base/289274 Log: NTB: MFV 58b88920: Document HW errata Add a comment describing the necessary ordering of modifications to the NTB Limit and Base registers. Authored by: Jon Mason Obtained from: Linux (Dual BSD/GPL driver) Sponsored by: EMC / Isilon Storage Division Modified: head/sys/dev/ntb/ntb_hw/ntb_hw.c Modified: head/sys/dev/ntb/ntb_hw/ntb_hw.c ============================================================================== --- head/sys/dev/ntb/ntb_hw/ntb_hw.c Tue Oct 13 23:42:13 2015 (r289273) +++ head/sys/dev/ntb/ntb_hw/ntb_hw.c Tue Oct 13 23:43:06 2015 (r289274) @@ -764,6 +764,11 @@ ntb_setup_xeon(struct ntb_softc *ntb) * which may hang the system. To workaround this use the second memory * window to access the interrupt and scratch pad registers on the * remote system. + * + * There is another HW errata on the limit registers -- they can only + * be written when the base register is (?)4GB aligned and < 32-bit. + * This should already be the case based on the driver defaults, but + * write the limit registers first just in case. */ if (HAS_FEATURE(NTB_REGS_THRU_MW)) /*
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