Mailinglist Archive: opensuse-factory (757 mails)

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Re: [opensuse-factory] tagmedia question
  • From: Volker Kuhlmann <hidden@xxxxxxxxxxxxxxx>
  • Date: Tue, 9 May 2006 20:22:45 +1200
  • Message-id: <20060509082245.GC5704@xxxxxxxxxxxxxxx>
> So the current kernel still does read-ahead past the end of the device? I had
> reported that for SuSE 9.0 I think, and the blabla was that I would be using an
> uncertified DVD/CD-RW drive.

While I don't want to argue about kernel developer's knowledge, this
does sound like buck-passing to me. Turning DMA off usually allows to
read a few more blocks, sometimes to the end. But when turning off
read-ahead (hdparm -a0) and suddenly all iso fs blocks become readable,
then my finger points at the kernel, not the drive. This was SuSE 9.2.

> Definitely padding the iso will help as long as noone
> tries raw-reading the iso back.

Ehh, I am reading ISOs back all the time and insist on continuing to do
so. Ignore Eberhard and pad after the ISO when burning. Btw in SuSE 9.2
150 blocks = 300k was not enough padding for DVDs. Of course this
doesn't help with disks already burnt.

> That bug should be fixed in the kernel, and
> exactly there.

Ack.

I've had Redmond-burnt CDs with 2 empty blocks after the last non-null
block, and 9.2 failed to read the last file on the CD. I doubt this CD
would have been unreadable under the other OS.

It's probably difficult to fix because the kernel block I/O layer
doesn't know anything about isofs (and mustn't - could be reiserfs on
the CD), and the whole CD technology doesn't supply the information of
what the last recorded block is, or something like that.

Volker

--
Volker Kuhlmann is list0570 with the domain in header
http://volker.dnsalias.net/ Please do not CC list postings to me.

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