Date: Thu, 25 Apr 1996 14:34:04 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: alk@Think.COM (Tony Kimball) Cc: questions@FreeBSD.ORG Subject: Re: bounce buffers Message-ID: <199604252134.OAA25496@phaeton.artisoft.com> In-Reply-To: <199604250653.BAA01917@compound.Think.COM> from "Tony Kimball" at Apr 25, 96 01:53:51 am
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> Under what circumstances are bounce buffers indicated? > Are they not indicated in all systems using >16MB DRAM? > My impression was that all such systems would require > bounce buffers in order to support DMA generally, while > no other systems would require bounce buffers. Bounce buffers are required for 24 bit (ISA) bus master DMA to addresses over 16M. If you are not using ISA cards, or an EISA system with a HiNT chipset, or a broken VLB card, you don't need bounce buffers. Normal EISA, normal VLB, and all PCI systems work without bounce buffers. Technically, if you had an Amiga, and FreeBSD was ported to it, or an Alpha with an EISA bus, and FreeBSD was ported to it, you'd need bounce buffers for the coprocessors that could only copy to/from "chip ram". Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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