Path: utzoo!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!dsinc!bagate!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga.hardware Subject: Re: 68030 options. Message-ID: <19944@cbmvax.commodore.com> Date: 18 Mar 91 18:25:39 GMT References: <47678@nigel.ee.udel.edu> Reply-To: daveh@cbmvax.commodore.com (Dave Haynie) Organization: Commodore, West Chester, PA Lines: 27 In article <47678@nigel.ee.udel.edu> tsarna@polar.bowdoin.edu (Tyler Sarna) writes: >In article <19871@cbmvax.commodore.com> of comp.sys.amiga.hardware, >Dave Haynie wrote: >> stale data in either cache after a DMA transfer. The A2091 software will >> actually flush the cache after an I/O operation completes, but in general, >Perfect timing, Dave! Someone just asked me how to flush the >cache(s), and I don't have the foggiest. The only way to do this, under 1.3, is to actually run the "movec dn, cacr" instruction. You'd have to read the cacr, set the "clear cache" bits for I and D caches, and then write it back. This will clear the caches properly for 68020 and 68030, but not for 68040 or any external cache that might need clearing. And it will break on a 68000, for example, which doesn't know about movec to cacr. Under 2.0, there's a system call to be used for cache clearing, which can be called for any system, and would even work with external caches (any external cache added to the system would vector in a call for its own cache hardware as well as any on-chip cache). > /// Tyler "Ty" Sarna E-Mail: tsarna@polar.bowdoin.edu -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "What works for me might work for you" -Jimmy Buffett