Date: Sat, 12 Oct 2002 15:06:16 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: hch@infradead.org Cc: wes@softweyr.com, dillon@apollo.backplane.com, vova@sw.ru, nate@root.org, arch@FreeBSD.ORG Subject: Re: Database indexes and ram Message-ID: <20021012.150616.129769790.imp@bsdimp.com> In-Reply-To: <20021012135245.A16453@infradead.org> References: <200210082051.g98KpjU1084793@apollo.backplane.com> <3DA4C271.37AACAA3@softweyr.com> <20021012135245.A16453@infradead.org>
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In message: <20021012135245.A16453@infradead.org>
Christoph Hellwig <hch@infradead.org> writes:
: On Wed, Oct 09, 2002 at 04:57:37PM -0700, Wes Peters wrote:
: > Linux solved this problem by refusing to do it. The candidates for DMA
: > transfers include skbufs and buffers from the disk buffer pool, both of
: > which are allocated from the lowest 4GB of physical ram when using PAE
: > mode.
:
: Umm, Linux _does_ DMA into any memory if the NIC/HBA/whatever supports
: it.
Unless the card is 64bit, it can't DMA past 4G.
Warner
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