amd64 ad0: TIMEOUT - READ_DMA on boot...

Fernando Schapachnik fernando at
Wed Sep 7 17:37:15 PDT 2005

En un mensaje anterior, Jeff D. Hamann escribió:
> I'm trying to set up a new amd64 FreeBSD 5.4 machine and when I 
> attempt to boot up for the first time (many time by now), I get 
> the following message(s):
> isa_dmainit(2, 40960) failed
> blah, blah, blah, then...
> ad0: 190782MB <WDC WD2000JB-00GVA0/08.02D08> [387621/16/53] at 
> ata0-master WDMA2
> ad0: TIMEOUT - READ_DMA retrying (2 retries left) LBA=390721905

6.0-BETA solved that for me (although on an old IDE disk). 
You can also try (at the cost of performance) to disable DMA 
in the BIOS and/or the OS.

Good luck.

Fernando P. Schapachnik
fernando at

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