linux-kernel - Re: ERROR: end_request: I/O error, dev fd0, sector 0

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Message-ID: <CA+icZUVhxHxoED2P7=kYqxYyg-8s3am4PSAvZLE8YSYAAHpaqA@mail.gmail.com>
Date:	Sun, 27 Nov 2011 14:52:18 +0100
From:	Sedat Dilek <sedat.dilek@...glemail.com>
To:	Robert Hancock <hancockrwd@...il.com>
Cc:	Jens Axboe <axboe@...nel.dk>, Tejun Heo <tj@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-next <linux-next@...r.kernel.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: ERROR: end_request: I/O error, dev fd0, sector 0

On Sat, Nov 26, 2011 at 5:52 PM, Robert Hancock <hancockrwd@...il.com> wrote:
> On 11/25/2011 06:53 AM, Sedat Dilek wrote:
>>
>> Hi,
>>
>> I am watching this issue for a long while, due to my
>> floppy-blacklist.conf file since next-20110603.
>>
>> The bad: The boot-process stalls for approx 10-13 secs when booting
>> into my Debian/sid i386 system.
>>
>> # dmesg | grep -A1 -B1 "end_request: I/O error, dev fd0, sector 0"
>> [    2.422854] sd 2:0:0:0: [sdb] Attached SCSI disk
>> [   15.289939] end_request: I/O error, dev fd0, sector 0
>> [   15.342914] EXT4-fs (sda5): mounted filesystem with ordered data
>> mode. Opts: (null)
>>
>> The funny part is my IBM laptop has no physical floppy drive!
>>
>> # dmesg | egrep -i 'floppy|fd0'
>> [    0.726358] Floppy drive(s): fd0 is 1.44M
>> [   15.289939] end_request: I/O error, dev fd0, sector 0
>>
>> If I blacklist "floppy" kernel-module, the boot-process is as expected
>> without the above mentionned delay.
>>
>> [ /etc/modprobe.d/floppy-blacklist.conf ]
>> # This file blacklists the floppy driver.
>> #
>> # XXX: Workaround: My IBM ThinkPad T40p (model 2374SG6) notebook has
>> no physical FDD
>> # dmesg from linux-next (next-20110603) says:
>> # [    0.755294] Floppy drive(s): fd0 is 1.44M
>> # [   15.238507] end_request: I/O error, dev fd0, sector 0
>> blacklist floppy
>> - EOF -
>>
>> I searched for the line and found bool blk_update_request() in
>> block/blk-core.c file (see [1]).
>>
>> I have attached kern.log and dmesg.
>>
>> Hope this helps to narrow down the issue.
>
> It looks like your laptop's BIOS indicates it has a floppy controller that's
> active:
>
> Nov 25 11:00:32 tbox kernel: [    0.060821] pnp 00:09: [io  0x03f0-0x03f5]
> Nov 25 11:00:32 tbox kernel: [    0.060825] pnp 00:09: [io  0x03f7]
> Nov 25 11:00:32 tbox kernel: [    0.060828] pnp 00:09: [irq 6]
> Nov 25 11:00:32 tbox kernel: [    0.060831] pnp 00:09: [dma 2]
> Nov 25 11:00:32 tbox kernel: [    0.060892] pnp 00:09: Plug and Play ACPI
> device, IDs PNP0700 (active)
>
> That's presumably why the floppy driver ends up being loaded. And apparently
> it does have a floppy controller, since the floppy driver seems able to talk
> to it. Maybe that model of laptop had an optional bay-mounted floppy drive
> or something?
>

Could be... next to CD_ROM bay maybe.

> I'm not sure there's a workaround for this at the kernel level, since the
> kernel probably can't determine if there's actually a floppy drive installed
> without trying to read from it (which is likely being triggered by partition
> probing or something). The read error will be what is triggering the message
> you saw.
>
> Is there a BIOS option to disable the floppy controller?
>

I have disabled "Floppy-Drive" in BIOS setup now (was set to
"enabled"), but I have still the modprobe backlist for floppy
activated.

Can you explain the stalling of ***10-12 seconds*** with a wrong FDD
BIOS setting?
That's really a long duration, with systemd my boot-process takes
approx 15-18 seconds.

Attached is the new dmesg output (kernel-config was not changed).

- Sedat -

View attachment "dmesg_3.2.0-rc3-next20111125.3-686-small.txt" of type "text/plain" (53047 bytes)