DMA failures on AMD64 with 4 GB RAM

[Attila Nagy]

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.

-- 
Attila Nagy                                   e-mail: Attila.Nagy at fsn.hu
Free Software Network (FSN.HU)                 phone: +3630 306 6758
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