Re: IDE cdrom problem with PLEXTOR DVDR PX-608AL

[Brad Rosser]

Hello Boris, Bart,

On Tue, Feb 26, 2008 at 12:45 AM, Borislav Petkov
<petkovbb@xxxxxxxxxxxxxx> wrote:
>
> On Mon, Feb 25, 2008 at 03:57:06PM +1000, Brad Rosser wrote:
> >
> > ... it would suggest the option 'hda=noprobe' was entered correctly?
>
>  ok, let's try something else: change the line "#if 0" to "#if 1" at the
>  beginning of kernel/params.c, it looks like:
>
>  #if 0
>  #define DEBUGP printk
>  #else
>  #define DEBUGP(fmt, a...)
>  #endif
>
>  rebuild your kernel, and reboot with it. Then, please send me that boot log to
>  see whether the kernel command line is being received from the boot loader and
>  what exactly is getting parsed. Thanks.

Boris,  I've done that; the output is in attached file dmesg.debug.out.

It looks to me that the kernel still found the IDE DVD drive (hda) ...
in addition
to the system messages when the system was up I found the ide_cd_mod
module loaded on top of 'cdrom' as normal.

>  Please see whether you can apply the patch Bart just sent and if that still gets
>  mangled and cannot be applied, consider making those changes to ide-cd.c by hand
>  - after all, there are only several lines that need to be changed so it won't
>  take that long.

Bart, I was able to apply that patch file you attached with no problems, and the
behaviour of the patched kernel changed as follows:

- no more 'confused' messages, nor the rush of other critical messages
that accompanied a system hang on one out of four tests yesterday.

- However, a new message that popped up twice; once after a few seconds
of network activity, and then about 15-20 seconds afterwards:

hda: ide_cd_check_ireason: wrong transfer direction!
hda: ide_cd_check_ireason: wrong transfer direction!

- also, I'm pretty sure that performance of both network and DVD drive suffered.

As to the last ... my new PC, on which I'm doing all this testing, has a gigabit
Realtek NIC.  It's hooked up via null UTP cable to my older machine which has
a 100Mb/s card.  ethtool shows that they both auto-negotiate to run at 100Mb/s
full duplex.  When I run my network test (pumping through /dev/zero across ssh
from the old machine to the new) the network stats tell me that I'm getting
10MB/s out of the link, which is what I would expect.

With the patched 2.6.25-rc2 kernel running with no activity reading the DVD
but the network going flat out (on the old PC's end) I noted that I was only
getting only 8.0 or 8.1 MB/sec, rather than the 10 MB/sec I've seen in the other
tests..  There was no other network traffic or cpu load on the machine(s).

Then, when I mounted a DVD disc and did a 'wc /mnt/*' of its contents
an iostat showed me that I was getting only about 6MB/sec out of the DVD
drive, which is less than I'd expect.  As soon as I killed the network send
iostat's report zoomed up to roughly 10MB/sec.  So it seemed to me that,
in addition to the 'wrong direction' messages, I was losing some performance
on both the NIC and the DVD drive.

Regards to you both,


Brad

Attachment: dmesg.debug.out
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