linux-kernel - Re: 2.6.20-rc6 libata PATA ATAPI CDROM is not working

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Date:	Tue, 20 Feb 2007 08:40:54 +0100
From:	"Joel Soete" <soete.joel@...rlet.be>
To:	"lsorense" <lsorense@...lub.uwaterloo.ca>
Cc:	"htejun" <htejun@...il.com>, "luming\.yu" <luming.yu@...il.com>,
	"alan" <alan@...hat.com>, "opslynx" <opslynx@...il.com>,
	"alan" <alan@...rguk.ukuu.org.uk>,
	"linux-kernel" <linux-kernel@...r.kernel.org>,
	"jgarzik" <jgarzik@...ox.com>
Subject: Re: 2.6.20-rc6 libata PATA ATAPI CDROM is not working

> [snip]
> > 
> > Hmm, readcd was trying to read 279884 blocks, while cdrecord said it
> > wrote 279882 blocks.
> > 
> yes and seems to be always the same:
> with new burned cd I got:
> # ll /MultiCd/cd060213.iso
> -rwxr-xr-x 1 root root 3213312 Feb 13  2006 /MultiCd/cd060213.iso
> 
> i.e. 3213312/2048 == 1569
> 
> while:
> readcd dev=/dev/hdd f=- | md5sum
> Read  speed:  1059 kB/s (CD   6x, DVD  0x).
> Write speed:   353 kB/s (CD   2x, DVD  0x).
> Capacity: 1571 Blocks = 3142 kBytes = 3 MBytes = 3 prMB
> Sectorsize: 2048 Bytes
> Copy from SCSI (1,1,0) disk to file '-'
> end:      1571
> Errno: 0 (Success), read_g1 scsi sendcmd: no error
> CDB:  28 00 00 00 06 00 00 00 23 00
> status: 0x2 (CHECK CONDITION)
> Sense Bytes:
> Sense Key: 0xFFFFFFFF [], Segment 0
> Sense Code: 0x00 Qual 0x00 (no additional sense information) Fru 0x0
> Sense flags: Blk 0 (not valid)
> cmd finished after 0.014s timeout 40s
> readcd: Success. Cannot read source disk
> readcd: Retrying from sector 1536.
> 
> so always Capacity == original image size + 2 ?
> 
> [snip]
> > 
> > There always seems to have been any issue with reading blocks from a cd
> > getting broken by the kernel doing readahead and getting failures by
> > trying to read past the end of the disc even though the user never asked
> > it to.  Sometimes your size just happens to hit a safe block size so the
> > readahead doesn't break.
> > 
> btw this tips:
> readcd dev=/dev/hdd sectors=0-1569 f=- | md5sum
> Read  speed:  1059 kB/s (CD   6x, DVD  0x).
> Write speed:   353 kB/s (CD   2x, DVD  0x).
> Capacity: 1571 Blocks = 3142 kBytes = 3 MBytes = 3 prMB
> Sectorsize: 2048 Bytes
> Copy from SCSI (1,1,0) disk to file '-'
> end:      1569
> addr:     1569 cnt: 33
> Time total: 5.436sec
> Read 3138.00 kB at 577.3 kB/sec.
> 6a1248783a21722816b972aa9bae9d5e  -
> 
> (adding sectors=0-1569 : 1569 being the size of the original image)
> 
> seems to work fine
> # md5sum /MultiCd/cd060213.iso
> 6a1248783a21722816b972aa9bae9d5e  /MultiCd/cd060213.iso
> 
> >> is the same wrong results.
> >>
> >> mmm I always used successfully dd method at my office with scsi cdrom drive 
> >> (even for bootable disk).
> > 
> > Well it seems some disks can be read that way, others can not.
> > 
> I would be curious to read same cd on scsi cdrom (at the office)?
> 
well here are the results with the cd I burned at home and in a scsi cd rw drive:
# dd if=/dev/rdsk/c1t4d0 bs=2048 | md5sum
1569+0 records in
1569+0 records out
6a1248783a21722816b972aa9bae9d5e  -

and also with readcd but an older release:

# readcd -version
readcd 1.11a19 (hppa1.1-hp-hpux11.00) Copyright (C) 1987, 1995-2002 Jörg Schilling

# readcd dev=1,4,0 f=- | md5sum           
Capacity: 1569 Blocks = 3138 kBytes = 3 MBytes = 3 prMB
Sectorsize: 2048 Bytes
Copy from SCSI (1,4,0) disk to file '-'
end:      1569
addr:     1569 cnt: 19
Time total: 6.239sec
Read 3138.00 kB at 503.0 kB/sec.
6a1248783a21722816b972aa9bae9d5e  -

I am very confused: cdrecord finaly do well its job on ide drive but what went
wrong for the check (cdrom drive? (but I don't have another model to test) or
some code in the kernel? (I don't think to have a small chance to put this ide
drive on a *nix system which could support ide and scsi hw)).

Any idea?

Cheers,
 	Joel	
> 
> 
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