[Forwarding to linux-ide again, because I wasn't subscribed earlier]
---------- Forwarded message ----------
Date: Sat, 8 Aug 2015 23:43:04 -0700 (PDT)
From: Christian Kujau <lists@xxxxxxxxxxxxxxx>
To: linuxppc-dev@xxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx, linux-ide@xxxxxxxxxxxxxxx
Subject: Re: 4.1-rc6: ATA link is slow to respond, please be patient
On Sat, 8 Aug 2015, Christian Kujau wrote:
> [Adding linux-ide@xxxxxxxxxxxxxxx]
>
> On Fri, 7 Aug 2015, Christian Kujau wrote:
> > this PowerBook G4 was running 3.16 for a while but now I wanted to upgrade
> > to latest mainline. However, during bootup the following happens:
> >
> > ===============================
> > [ 2.237102] ata1: PATA max UDMA/100 irq 39
> > [ 2.401708] ata1.00: ATA-8: SAMSUNG HM061GC, LR100-10, max UDMA/100
> > [ 2.401764] ata1.00: 117231408 sectors, multi 16: LBA48
> > [ 2.417633] ata1.00: configured for UDMA/100
> > [ 44.918102] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
> > [ 44.920452] ata1.00: failed command: READ DMA
> > [ 44.922725] ata1.00: cmd c8/00:88:64:c2:12/00:00:00:00:00/e0 tag 0 dma 69632 in
> > [ 44.927257] ata1.00: status: { DRDY }
> > [ 49.971784] ata1.00: qc timeout (cmd 0xec)
> > [ 49.976529] ata1.00: failed to IDENTIFY (I/O error, err_mask=0x4)
> > [ 49.978908] ata1.00: revalidation failed (errno=-5)
> > [ 55.019662] ata1: link is slow to respond, please be patient (ready=0)
> > [ 60.007677] ata1: device not ready (errno=-16), forcing hardreset
> > [ 60.012670] ata1: soft resetting link
> > [ 60.193638] ata1.00: configured for UDMA/100
> > [ 60.196158] ata1.00: device reported invalid CHS sector 0
> > [ 60.198610] ata1: EH complete
> > ===============================
> >
> > This happens only once, but systemd thinks there's a hard problem and will
> > drop to a recovery shell. I can start sshd and login remotely and then the
> > system appears to be running just fine.
I played around with libata* kernel parameters, the only "success" I had
was with libata.dma=0 - which disables DMA and the system booted without
the error. But of course the disk throughput was much slower - is there a
way to enable DMA again once the system is booted? "hdparm -d" would
return HDIO_SET_DMA, of course[0].
Tried something more drastic and disabled libata completely and enabled
CONFIG_IDE (and CONFIG_BLK_DEV_IDE_PMAC) again and a similar error appears
(sometimes) during bootup:
[ 39.971392] ide-pmac lost interrupt, dma status: 8480
[ 39.972704] hda: lost interrupt
[ 39.973951] hda: dma_intr: status=0xd8 { Busy }
[ 39.975231] hda: possibly failed opcode: 0x25
[ 39.978855] hda: DMA disabled
[ 40.019388] ide0: reset: success
But the host seems to recover more quickly and systemd wasn't thrown off
by the small ATA delay. But DMA got disabled again :-\
Ideas welcome! :-)
Christian.
[0] https://ata.wiki.kernel.org/index.php/Libata_FAQ
> > This happened in 4.2.0-rc5 so I went back a few versions and found that
> > 4.1-rc5 was OK (the error does not show up and the system boots just fine)
> > and 4.1-rc6 is not.
> >
>
> After more digging around I noticed that the same error (with
> changed wording) happens with a Debian 3.16.0-4-powerpc kernel - so it
> doesn't appear to be a recent regression as I suspected at first:
>
> ==================================
> [ 46.907147] ata1: drained 572 bytes to clear DRQ
> [ 46.907166] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
> [ 46.908419] ata1.00: failed command: READ DMA
> [ 46.909058] ata1.00: cmd c8/00:80:9c:f9:60/00:00:00:00:00/e0 tag 0 dma 65536 in
> res 40/00:fe:00:00:00/00:00:00:00:00/40 Emask 0x20 (host bus error)
> [ 46.910303] ata1.00: status: { DRDY }
> [ 46.970579] ata1.00: configured for UDMA/100
> [ 46.971853] ata1.00: device reported invalid CHS sector 0
> [ 46.972524] ata1: EH complete
> ==================================
>
> Also, the error cannot repduced as reliably as I thought: sometimes, the
> machine just boots w/o a hitch - and that might be the reasons why my
> bisect attempts failed and incorrectly blamed totally unrelated commits:
> after each "git bisect {good,bad}" (+compiling) I rebooted but there was a
> chance that the system came up just fine / showed the same ATA error and
> thus falsified the git-bisect results.
>
> I noticed that with this Debian 3.16 kernel, it happens less often when I
> use the "irqpoll" option. But with 4.2-rc5 this doesn't seem to help much,
> the system still hangs during boot but continues after the "EH complete "
> message. And it doesn't appear afterwards, I can read from my root disk
> just fine and a long SMART check also comes back fine.
>
> Because the error only appears to happen on the very first access after a
> reboot, I tried to boot with rootdelay=30 - but of course then it just
> waits "before" accessing the root disk. I'd need a magic option to wait a
> few seconds "after" the first disk access, so that the boot framework
> ("systemd") won't be thrown off when /dev/sda isn't responding as fast as
> expected.
>
> What _does_ seem to help a bit was to disable the the swap device, which
> is configured as an encrypted dm-device here - and systemd was almost
> always stumbling over this particular service during bootup. Because of
> the ATA timeout, the dm-device could not be setup correctly and systemd
> would bail out and drop me into a recovery shell. Without the swap device,
> systemd would skip setting up swap and boot just fine (most of the time)
> and I can setup swap once the system has been booted. So...there's that.
>
> It's still a mystery to me why /dev/sda is only behaving weird on its
> first access.
>
> I've cc'ed linux-ide, maybe somebody has an idea on that?
>
> dmesg & .config: http://nerdbynature.de/bits/v4.1-rc6/
>
> Thanks,
> Christian.
>
>
> > Unfortunately a git-bisect between these two versions went completly off
> > the charts, I don't know what happened here:
> > ==================================
> > first bad commit:
> >
> > 0fa372b6c95013af1334b3d5c9b5f03a70ecedab is the first bad commit
> > commit 0fa372b6c95013af1334b3d5c9b5f03a70ecedab
> > Author: Takashi Iwai <tiwai@xxxxxxx>
> > Date: Wed May 27 16:17:19 2015 +0200
> >
> > ALSA: hda - Fix noise on AMD radeon 290x controller
> > ==================================
> >
> > I don't have this driver (or ALSA) even selected. I can reproduce this
> > error pretty reliably and I'd like to attempt another git-bisect
> > run when I'm more awake. But maybe somebody recognizes this error and
> > has a hint where this could come from?
> >
> > dmesg & .config: http://nerdbynature.de/bits/v4.1-rc6/
> >
> > Thanks,
> > Christian.
> > --
> > BOFH excuse #225:
> >
> > It's those computer people in X {city of world}. They keep stuffing things up.
> >
>
> --
> BOFH excuse #263:
>
> It's stuck in the Web.
>
--
BOFH excuse #316:
Elves on strike. (Why do they call EMAG Elf Magic)
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