5.3 RC1 CD Boot
noackjr at alumni.rice.edu
Mon Nov 1 11:35:57 PST 2004
> What I suspect has happened is that sometime since 5.2.1 the ATA subsystem
> has started using DMA with ATAPI devices by default. I just put 5.3 RC1 on
> my laptop last night by booting with a 5.2.1 CD and using the 5.3 cd has
> the media source.
> Once the OS was installed, I was still unable to read any CDs
> (MEDIA_SENSE_BIG error or something similar). I saw Soeren advising
> someone to set hw.ata.atapi_dma=0 in loader.conf in a somewhat releated
> post. Doing this worked for me.
> I wonder whether there is a way to do this with the Install CD?
> Perhaps 4.3 should be released with atapi_dma disabled by default to cater
> for those of use with flaky hardware?
> Aside from that, 5.3 RC1 feels slick on my Compaq Presario 2105. Very nice
> job guys.
ATAPI DMA was enabled because some newer drives refuse to work with it
disabled and high-speed CD and DVD burners need it enabled to function at
full-speed. It was an issue where leaving it disabled was resulting in
*more* problem reports than enabling it would. Thus, the move to a more
"modern" default. ATAPI DMA is only enabled when the device supports
UDMA33, which is an attempt to do the right thing as much as possible.
Sadly, there are always some setups that fall through the cracks...
Regardless, there are several ways around it when installing from the CD:
1) Set hw.ata.atapi_dma=0 at the CD's loader prompt (menu #6)
2) Use safe mode, which disables ATAPI DMA among other things (menu #3)
If you were unable to install, it seems like retrying in safe mode is the
logical next step...
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