Date: Mon, 11 Mar 2013 15:22:47 -0700 From: Jim Harris <jimharris@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: Dag-Erling Sm??rgrav <des@des.no>, Lev Serebryakov <lev@serebryakov.spb.ru>, arch@freebsd.org Subject: Re: Unmapped buffers: to be merged in several days Message-ID: <CAJP=Hc9V9HVpdevD3=Qgk812CYwbmc-Q4HgtPyupb7zTfmTB6g@mail.gmail.com> In-Reply-To: <20130311211158.GE3794@kib.kiev.ua> References: <20130311091852.GR3794@kib.kiev.ua> <86k3pe1cl3.fsf@ds4.des.no> <20130311182454.GX3794@kib.kiev.ua> <329178079.20130312010425@serebryakov.spb.ru> <20130311211158.GE3794@kib.kiev.ua>
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On Mon, Mar 11, 2013 at 2:11 PM, Konstantin Belousov <kostikbel@gmail.com>wrote: > FWIW, I tried to get an Intel documentation for IOAT engine which should > allow to perform the XOR checksumming of the unmapped buffers, suitable > for e.g. hardware-assisted software raid5, but did not succeeded. > Please note that XOR checksumming support only exists in the E5-1600/2400/2600/4600 series (Sandy Bridge Xeon) and C5500/C3500 series (Jasper Forest - based on Nehalem Xeon) processors. The SNB Xeon series EDS section for IOAT isn't public, but the Jasper Forest datasheet volume 2 does contain the register interfaces. See sections 3.9 and section 3.10. The ioat HW interface for XOR is the same for both series save for some delta in errata. http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/xeon-c5500-c3500-datasheet-vol-2.pdf Also note there is an ioat driver (DMA operations only) on the user/jimharris/ioat branch in the FreeBSD SVN repo. The Linux ioat driver with XOR support is dual-licensed BSD/GPL. Regards, -Jim
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