Re: DMA failures on AMD64 with 4 GB RAM

From: Scott Long (scottl_at_samsco.org)
Date: 11/28/05

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    Date: Mon, 28 Nov 2005 10:04:03 -0700
To: Søren Schmidt <sos@deepcore.dk>

    Søren Schmidt wrote:

    > Attila Nagy wrote:
    >
    >> Hello,
    >>
    >> There is a problem with recent ATA drivers on (at least) AMD64 with 4
    >> GB of RAM, which can be triggered by synchronizing a geom mirror
    >> provider to another one (or generally a bigger disk I/O, I guess).
    >>
    >> The machine dies instantly with the following:
    >> GEOM_MIRROR: Device hars: rebuilding provider ad6.
    >> ad6: setting up DMA failed
    >> ad6: setting up DMA failed
    >>
    >> This is true either on RELENG_6 and on HEAD as of today.
    >>
    >> There are two workarounds:
    >> - use the ata driver from RELENG_6 which is not older than 2005.10.08
    >> - set hw.physmem smaller than 4G
    >>
    >> Are there any chances to resolve this issue?
    >>
    >> Thank you.
    >>
    >> ps: there was some discussion about this:
    >> http://marc.theaimsgroup.com/?l=freebsd-amd64&m=113034973432742&w=2
    >> where Søren said it might be busdma, not the ata driver and Scott
    >> promised to look into that.
    >
    >
    > The resolution was that busdma doesn't work as advertised in the man
    > page, and that scottl would look into it.
    >
    > -Søren

    Well, the more accurate statement is that the manpage is not the
    authoritative design document, but rather a poorly adapted
    representation of how the subsystem might work on NetBSD =-) So
    busdma needs to be fixed to provide what the drivers need, and
    the manpage needs to be fixed to reflect how things actually work.

    In any case ATA still doesn't come anywhere close to conforming to
    the busdma API, and I doubt that me rewriting the manpage will fix
    that.

    Scott

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    Relevant Pages

    • Re: DMA failures on AMD64 with 4 GB RAM
      ... >> The resolution was that busdma doesn't work as advertised in the man ... > busdma needs to be fixed to provide what the drivers need, ... > the manpage needs to be fixed to reflect how things actually work. ... Please mark ATA as broken for> 4G of memory then, ...
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