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

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Date:	Sat, 17 Feb 2007 18:26:42 +0000
From:	Joel Soete <soete.joel@...rlet.be>
To:	Lennart Sorensen <lsorense@...lub.uwaterloo.ca>
CC:	Tejun Heo <htejun@...il.com>, Luming Yu <luming.yu@...il.com>,
	Alan Cox <alan@...hat.com>, Ioan Ionita <opslynx@...il.com>,
	Alan <alan@...rguk.ukuu.org.uk>, linux-kernel@...r.kernel.org,
	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)?

Cheers,
	Joel	
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