Messages in this thread | | | Date | Sat, 17 Aug 2002 19:30:52 +0100 | From | Anton Altaparmakov <> | Subject | Re: IDE? |
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At 19:16 17/08/02, Jan-Benedict Glaw wrote: >On Fri, 2002-08-16 18:35:29 -0700, Linus Torvalds <torvalds@transmeta.com> >wrote in message <Pine.LNX.4.44.0208161822130.1674-100000@home.transmeta.com>: > > On Fri, 16 Aug 2002, Alexander Viro wrote: > > > - in particular, it would only bother with PCI (or better) > > controllers, and with UDMA-only setups. >[...] > > And then in five years, in Linux-3.2, we might finally just drop support > > for the old IDE code with PIO etc. Inevitably some people will still use > >That's bad. Then, you're nailed to use old kernels without having >possibilities of recent kernels only because you're working with eg. old >Alphas, PCMCIA-IDE things or so? Bad, bad, badhorribly bad. Even it's >sloooow, there'll always some need for PIO-only controller support...
I don't think it is possible to have DMA only drivers. On DMA failure/timeouts/whatever, the current DMA drivers always fall back to PIO mode and this is a good thing. Otherwise many transfers would simply fail. Dropping PIO mode fallback would mean a lot of IO errors. Any system put under stress will at some point fall back to PIO mode (at least judgjing from the limited number of systems I have) because it doesn't manage to do the DMA transfers in time. That was very visible during the period when Andre's new IDE core went into 2.5.something_early and it turned out that PIO was broken at that point. For example my VIA box was running just fine then in DMA mode but as soon as I put it under stress it blew up due to it falling out of DMA and the then broken PIO mode... And VIA686b is mainstream hardware...
Best regards,
Anton
-- "I've not lost my mind. It's backed up on tape somewhere." - Unknown -- Anton Altaparmakov <aia21 at cantab.net> (replace at with @) Linux NTFS Maintainer / IRC: #ntfs on irc.openprojects.net WWW: http://linux-ntfs.sf.net/ & http://www-stu.christs.cam.ac.uk/~aia21/
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