Re: Linux 2.4.18: short dd read from IDE cdrom
Erik Andersen (andersen@codepoet.org)
Tue, 3 Sep 2002 01:35:25 -0600
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/
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