Re: Linux 2.4.18: short dd read from IDE cdrom

From: Erik Andersen (andersen@codepoet.org)
Date: Tue Sep 03 2002 - 02:35:25 EST


On Tue Sep 03, 2002 at 04:49:12PM +0930, Jonathan Woithe wrote:
> Hi all
>
> Yesterday I reported a problem to lkml I observed with `dd' and ide cds:
> > For a number of years now I have duplicated cds using
> > dd if=/dev/cdrom of=foo.iso
> > cdrecord ... foo.iso
> > :
> > Today I tried the same trick under 2.4.18 and struck a problem: the kernel
> > would not read the complete CD image. ...
>
> After further testing, it seems that turning off dma using "hdparm -d 0
> /dev/hdc" allows things to work as expected - the full disk can be read and
> the resulting image is intact. It appears therefore that the problem may

Interesting. When DMA is enabled does running
    blockdev --setra 0 /dev/cdrom
make any difference?

 -Erik

--
Erik B. Andersen             http://codepoet-consulting.com/
--This message was written using 73% post-consumer electrons--
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/



This archive was generated by hypermail 2b29 : Sat Sep 07 2002 - 22:00:17 EST