Date: Mon, 23 Nov 2009 12:53:24 -0800 From: Pyun YongHyeon <pyunyh@gmail.com> To: Joerg Sonnenberger <joerg@britannica.bec.de> Cc: svn-src-all@freebsd.org Subject: Re: svn commit: r199670 - head/sys/dev/bge Message-ID: <20091123205324.GC1214@michelle.cdnetworks.com> In-Reply-To: <20091123010511.GA14572@britannica.bec.de> References: <200911222050.nAMKoRYh029141@svn.freebsd.org> <20091123010511.GA14572@britannica.bec.de>
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On Mon, Nov 23, 2009 at 02:05:11AM +0100, Joerg Sonnenberger wrote: > On Sun, Nov 22, 2009 at 08:50:27PM +0000, Pyun YongHyeon wrote: > > Log: > > Fix two long standing bugs on bge(4). Most pre BCM5755 controllers > > have a DMA bug when buffer address crosses a multiple of the 4GB > > boundary(e.g. 4GB, 8GB, 12GB etc). > > Does this only affect transfers that *cross* a 4GB boundary or does it > also affect transfers that *end* at a 4GB boundary? E.g. if the mbuf > cluster starts at 0xffffff00 with size 0x100 -- will the DMA engine > stall happen or not? > AFAIK publicly available datasheet explicitly mentions 4GB boundary limitation(page 153). For BCM5704 case, the datasheet also says buffer descriptors that ends exactly on any multiple of 4GB, BCM5704 will generate host address overflow error even though the buffer descriptor does not actually cross over the 4GB boundary (page 213). I have no idea how to address this specific issue on BCM5704 except allocating more size than needed descriptor size though. > Joerg
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