Patchwork DMA doesn't work since "make ata port as parent device of scsi host"

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Submitter Jörg Sommer
Date March 15, 2012, 1:48 a.m.
Message ID <20120315014807.GA3051@alea.gnuu.de>
Download mbox | patch
Permalink /patch/146820/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Jörg Sommer - March 15, 2012, 1:48 a.m.
Hi,

I'm getting these messages in a KVM virtualized host and the access to
the disks is very slow. Using libata.dma=0 suppresses the warnings, but
the disks are still slow.

[    3.117419] pata-macio 0.00020000:ata-1: Activating pata-macio chipset Heathrow ATA, Apple bus ID 0
[    3.121637] scsi0 : pata_macio
[    3.123071] ata1: PATA max MWDMA2 irq 17
[    3.289181] ata1.00: ATA-7: QEMU HARDDISK, 1.0,1, max UDMA/100
[    3.290843] ata1.00: 3906250 sectors, multi 16: LBA48 
[    3.296526] ata1.01: ATA-7: QEMU HARDDISK, 1.0,1, max UDMA/100
[    3.301789] ata1.01: 1953125 sectors, multi 16: LBA48 
[    3.309588] ata1.00: configured for MWDMA2
[    3.322195] ata1.01: configured for MWDMA2
[    3.324375] scsi 0:0:0:0: Direct-Access     ATA      QEMU HARDDISK    1.0, PQ: 0 ANSI: 5
[    3.335681] sd 0:0:0:0: [sda] 3906250 512-byte logical blocks: (2.00 GB/1.86 GiB)
[    3.342118] scsi 0:0:1:0: Direct-Access     ATA      QEMU HARDDISK    1.0, PQ: 0 ANSI: 5
[    3.349779] sd 0:0:0:0: [sda] Write Protect is off
[    3.351558] sd 0:0:1:0: [sdb] 1953125 512-byte logical blocks: (1.00 GB/953 MiB)
[    3.361555] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[    3.377923]  sda: unknown partition table
[    3.387499] sd 0:0:1:0: [sdb] Write Protect is off
[    3.389902] sd 0:0:0:0: [sda] Attached SCSI disk
[    3.395363] sd 0:0:1:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[    3.407258]  sdb: unknown partition table
[    3.410463] sd 0:0:1:0: [sdb] Attached SCSI disk
[    4.137709] pata-macio 0.00021000:ata-2: Activating pata-macio chipset Heathrow ATA, Apple bus ID 0
[    4.141529] scsi1 : pata_macio
[    4.142797] ata2: PATA max MWDMA2 irq 19
[    4.302209] ata2.00: ATAPI: QEMU DVD-ROM, 1.0,1, max UDMA/100
[    4.306595] ata2.00: configured for MWDMA2
[    4.309863] scsi 1:0:0:0: CD-ROM            QEMU     QEMU DVD-ROM     1.0, PQ: 0 ANSI: 5
[    5.158307] pata-macio 0.00022000:ata-3: Activating pata-macio chipset Heathrow ATA, Apple bus ID 0
[    5.163497] scsi2 : pata_macio
[    5.164792] ata3: PATA max MWDMA2 irq 21
[    5.166278] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[    5.168587] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[    5.171020] mousedev: PS/2 mouse device common for all mice
[    5.174973] device-mapper: ioctl: 4.22.0-ioctl (2011-10-19) initialised: dm-devel@redhat.com
[    5.178453] zcache: cleancache enabled using kernel transcendent memory and compression buddies
[    5.181809] TCP cubic registered
[    5.183188] NET: Registered protocol family 17
[    5.184472] Registering the dns_resolver key type
[    5.201059] registered taskstats version 1
[    5.203025] Running tests on trace events:

[   10.524655] EXT4-fs (sda): couldn't mount as ext3 due to feature incompatibilities
[   10.528671] EXT4-fs (sda): couldn't mount as ext2 due to feature incompatibilities
[   10.574484] zcache: created ephemeral tmem pool, id=0, client=65535
[   10.577259] EXT4-fs (sda): mounted filesystem without journal. Opts: (null)
[   10.579299] VFS: Mounted root (ext4 filesystem) readonly on device 8:0.
[   10.583854] Freeing unused kernel memory: 280k freed
[   40.828762] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
[   40.830697] ata1.00: failed command: READ DMA
[   40.831985] ata1.00: cmd c8/00:c8:38:22:00/00:00:00:00:00/e0 tag 0 dma 102400 in
[   40.831992]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x20 (host bus error)
[   40.840162] ata1.00: status: { DRDY }
[   45.923821] ata1.00: qc timeout (cmd 0xec)
[   45.925142] ata1.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[   45.926957] ata1.00: revalidation failed (errno=-5)
[   50.975553] ata1: link is slow to respond, please be patient (ready=0)
[   55.974506] ata1: device not ready (errno=-16), forcing hardreset
[   55.976336] ata1: soft resetting link
[   56.137659] ata1.00: configured for MWDMA2
[   56.142009] ata1.01: configured for MWDMA2
[   56.143237] ata1.00: device reported invalid CHS sector 0
[   56.144780] sd 0:0:0:0: [sda]  Result: hostbyte=0x00 driverbyte=0x08
[   56.146859] sd 0:0:0:0: [sda]  Sense Key : 0xb [current] [descriptor]
[   56.148833] Descriptor sense data with sense descriptors (in hex):
[   56.150542]         72 0b 00 00 00 00 00 0c 00 0a 80 00 00 00 00 00 
[   56.153138]         00 00 00 00 
[   56.154286] sd 0:0:0:0: [sda]  ASC=0x0 ASCQ=0x0
[   56.155722] sd 0:0:0:0: [sda] CDB: cdb[0]=0x28: 28 00 00 00 22 38 00 00 c8 00
[   56.161462] end_request: I/O error, dev sda, sector 8760
[   56.163069] ata1: EH complete
[   86.870671] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
[   86.872494] ata1.00: failed command: READ DMA
[   86.873741] ata1.00: cmd c8/00:c0:40:22:00/00:00:00:00:00/e0 tag 0 dma 98304 in
[   86.873748]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x20 (host bus error)
[   86.877995] ata1.00: status: { DRDY }
[   91.961330] ata1.00: qc timeout (cmd 0xec)
[   91.962699] ata1.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[   91.964398] ata1.00: revalidation failed (errno=-5)
[   97.014555] ata1: link is slow to respond, please be patient (ready=0)
[  102.016502] ata1: device not ready (errno=-16), forcing hardreset
[  102.018329] ata1: soft resetting link
[  102.182355] ata1.00: configured for MWDMA2
[  102.186312] ata1.01: configured for MWDMA2
[  102.187498] ata1.00: device reported invalid CHS sector 0
[  102.189078] ata1: EH complete
[  132.862149] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
[  132.864011] ata1.00: failed command: READ DMA
[  132.865674] ata1.00: cmd c8/00:c0:40:22:00/00:00:00:00:00/e0 tag 0 dma 98304 in
[  132.865682]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x20 (host bus error)
[  132.869786] ata1.00: status: { DRDY }
[  137.949377] ata1.00: qc timeout (cmd 0xec)
[  137.950632] ata1.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[  137.952549] ata1.00: revalidation failed (errno=-5)
[  142.954461] ata1: link is slow to respond, please be patient (ready=0)

I've tracked this down to „ata: make ata port as parent device of scsi
host“ (9a6d6a2ddabbd32c07f6a38b659e5f3db319fa5a) with git biset.

    ata: make ata port as parent device of scsi host
    
    Currently, the device tree of ata port and scsi host looks as below,
    
            /sys/devices/pci0000:00/0000:00:1f.2    (ahci controller)
            |-- ata1                                (ata port)
            |-- host0                               (scsi host)
               |-- target0:0:0                      (scsi target)
                   |-- 0:0:0:0                      (disk)
    
    This patch makes ata port as parent device of scsi host, then it becomes
    
            /sys/devices/pci0000:00/0000:00:1f.2    (ahci controller)
            |-- ata1                                (ata port)
                |-- host0                           (scsi host)
                    |-- target0:0:0                 (scsi target)
                        |-- 0:0:0:0                 (disk)
    
    With this change, the ata port runtime PM is easier.
    For example, the ata port runtime suspend will happen as,
    
    disk suspend --> scsi target suspend --> scsi host suspend --> ata port
    suspend.
    
    Acked-by: Tejun Heo <tj@kernel.org>
    Signed-off-by: Lin Ming <ming.m.lin@intel.com>
    Signed-off-by: Jeff Garzik <jgarzik@redhat.com>


Can you tell, what might be wrong?

% cat /proc/cpuinfo
processor	: 0
cpu		: 7455, altivec supported
clock		: 798.720000MHz
revision	: 3.3 (pvr 8001 0303)
bogomips	: 48.58
timebase	: 18432000
platform	: PowerMac
model		: PowerBook6,3
machine		: PowerBook6,3
motherboard	: PowerBook6,3 MacRISC3 Power Macintosh
detected as	: 287 (iBook G4)
pmac flags	: 0000001b
L2 cache	: 256K unified
pmac-generation	: NewWorld
Memory		: 640 MB

# qemu-system-ppc -enable-kvm -M mac99 -cpu G4 -k de \
  -kernel /boot/vmlinuz-3.3.0-rc5 \
  -append 'root=/dev/sda ro console=ttyPZ0 zcache' \
  -hda /mnt/data/debian-base-root.raw -hdb /mnt/data/debian-base-var.raw

Bye, Jörg.
Lin Ming - March 15, 2012, 3:26 a.m.
On Thu, 2012-03-15 at 09:59 +0800, Lin Ming wrote:
> On Thu, 2012-03-15 at 02:48 +0100, Jörg Sommer wrote:
> > Hi,
> > 
> > I'm getting these messages in a KVM virtualized host and the access to
> > the disks is very slow. Using libata.dma=0 suppresses the warnings, but
> > the disks are still slow.
> 
> Hi Jörg,
> 
> Let me try to reproduce this issue first.

I tried below commands on x86_32, but can't reproduce it.

qemu-system-i386 -kernel /root/vmlinuz-3.3.0-rc7 -append "root=/dev/sda1
zcache" -hda /root/debian-32.img -hdb /root/data.img

Maybe because i386 uses different ata controller than ppc(ata_piix vs
pata-macio).

I'll try qemu-system-ppc.

Did you need to run some workload to trigger these warings?
Or did you get these warnings right after booting the VM?

Would you please try to disable ata port runtime pm?
You can disable it by, for example,

# echo on > /sys/devices/pci0000:00/0000:00:01.1/ata1/control

You need to change above path of "ata1" in the sysfs of your VM.

Thanks,
Lin Ming

> 
> Thanks for the report.
> Lin Ming
> 
> > 
> > [    3.117419] pata-macio 0.00020000:ata-1: Activating pata-macio chipset Heathrow ATA, Apple bus ID 0
> > [    3.121637] scsi0 : pata_macio
> > [    3.123071] ata1: PATA max MWDMA2 irq 17
> > [    3.289181] ata1.00: ATA-7: QEMU HARDDISK, 1.0,1, max UDMA/100
> > [    3.290843] ata1.00: 3906250 sectors, multi 16: LBA48 
> > [    3.296526] ata1.01: ATA-7: QEMU HARDDISK, 1.0,1, max UDMA/100
> > [    3.301789] ata1.01: 1953125 sectors, multi 16: LBA48 
> > [    3.309588] ata1.00: configured for MWDMA2
> > [    3.322195] ata1.01: configured for MWDMA2
> > [    3.324375] scsi 0:0:0:0: Direct-Access     ATA      QEMU HARDDISK    1.0, PQ: 0 ANSI: 5
> > [    3.335681] sd 0:0:0:0: [sda] 3906250 512-byte logical blocks: (2.00 GB/1.86 GiB)
> > [    3.342118] scsi 0:0:1:0: Direct-Access     ATA      QEMU HARDDISK    1.0, PQ: 0 ANSI: 5
> > [    3.349779] sd 0:0:0:0: [sda] Write Protect is off
> > [    3.351558] sd 0:0:1:0: [sdb] 1953125 512-byte logical blocks: (1.00 GB/953 MiB)
> > [    3.361555] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
> > [    3.377923]  sda: unknown partition table
> > [    3.387499] sd 0:0:1:0: [sdb] Write Protect is off
> > [    3.389902] sd 0:0:0:0: [sda] Attached SCSI disk
> > [    3.395363] sd 0:0:1:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
> > [    3.407258]  sdb: unknown partition table
> > [    3.410463] sd 0:0:1:0: [sdb] Attached SCSI disk
> > [    4.137709] pata-macio 0.00021000:ata-2: Activating pata-macio chipset Heathrow ATA, Apple bus ID 0
> > [    4.141529] scsi1 : pata_macio
> > [    4.142797] ata2: PATA max MWDMA2 irq 19
> > [    4.302209] ata2.00: ATAPI: QEMU DVD-ROM, 1.0,1, max UDMA/100
> > [    4.306595] ata2.00: configured for MWDMA2
> > [    4.309863] scsi 1:0:0:0: CD-ROM            QEMU     QEMU DVD-ROM     1.0, PQ: 0 ANSI: 5
> > [    5.158307] pata-macio 0.00022000:ata-3: Activating pata-macio chipset Heathrow ATA, Apple bus ID 0
> > [    5.163497] scsi2 : pata_macio
> > [    5.164792] ata3: PATA max MWDMA2 irq 21
> > [    5.166278] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
> > [    5.168587] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
> > [    5.171020] mousedev: PS/2 mouse device common for all mice
> > [    5.174973] device-mapper: ioctl: 4.22.0-ioctl (2011-10-19) initialised: dm-devel@redhat.com
> > [    5.178453] zcache: cleancache enabled using kernel transcendent memory and compression buddies
> > [    5.181809] TCP cubic registered
> > [    5.183188] NET: Registered protocol family 17
> > [    5.184472] Registering the dns_resolver key type
> > [    5.201059] registered taskstats version 1
> > [    5.203025] Running tests on trace events:
> > 
> > [   10.524655] EXT4-fs (sda): couldn't mount as ext3 due to feature incompatibilities
> > [   10.528671] EXT4-fs (sda): couldn't mount as ext2 due to feature incompatibilities
> > [   10.574484] zcache: created ephemeral tmem pool, id=0, client=65535
> > [   10.577259] EXT4-fs (sda): mounted filesystem without journal. Opts: (null)
> > [   10.579299] VFS: Mounted root (ext4 filesystem) readonly on device 8:0.
> > [   10.583854] Freeing unused kernel memory: 280k freed
> > [   40.828762] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
> > [   40.830697] ata1.00: failed command: READ DMA
> > [   40.831985] ata1.00: cmd c8/00:c8:38:22:00/00:00:00:00:00/e0 tag 0 dma 102400 in
> > [   40.831992]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x20 (host bus error)
> > [   40.840162] ata1.00: status: { DRDY }
> > [   45.923821] ata1.00: qc timeout (cmd 0xec)
> > [   45.925142] ata1.00: failed to IDENTIFY (I/O error, err_mask=0x4)
> > [   45.926957] ata1.00: revalidation failed (errno=-5)
> > [   50.975553] ata1: link is slow to respond, please be patient (ready=0)
> > [   55.974506] ata1: device not ready (errno=-16), forcing hardreset
> > [   55.976336] ata1: soft resetting link
> > [   56.137659] ata1.00: configured for MWDMA2
> > [   56.142009] ata1.01: configured for MWDMA2
> > [   56.143237] ata1.00: device reported invalid CHS sector 0
> > [   56.144780] sd 0:0:0:0: [sda]  Result: hostbyte=0x00 driverbyte=0x08
> > [   56.146859] sd 0:0:0:0: [sda]  Sense Key : 0xb [current] [descriptor]
> > [   56.148833] Descriptor sense data with sense descriptors (in hex):
> > [   56.150542]         72 0b 00 00 00 00 00 0c 00 0a 80 00 00 00 00 00 
> > [   56.153138]         00 00 00 00 
> > [   56.154286] sd 0:0:0:0: [sda]  ASC=0x0 ASCQ=0x0
> > [   56.155722] sd 0:0:0:0: [sda] CDB: cdb[0]=0x28: 28 00 00 00 22 38 00 00 c8 00
> > [   56.161462] end_request: I/O error, dev sda, sector 8760
> > [   56.163069] ata1: EH complete
> > [   86.870671] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
> > [   86.872494] ata1.00: failed command: READ DMA
> > [   86.873741] ata1.00: cmd c8/00:c0:40:22:00/00:00:00:00:00/e0 tag 0 dma 98304 in
> > [   86.873748]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x20 (host bus error)
> > [   86.877995] ata1.00: status: { DRDY }
> > [   91.961330] ata1.00: qc timeout (cmd 0xec)
> > [   91.962699] ata1.00: failed to IDENTIFY (I/O error, err_mask=0x4)
> > [   91.964398] ata1.00: revalidation failed (errno=-5)
> > [   97.014555] ata1: link is slow to respond, please be patient (ready=0)
> > [  102.016502] ata1: device not ready (errno=-16), forcing hardreset
> > [  102.018329] ata1: soft resetting link
> > [  102.182355] ata1.00: configured for MWDMA2
> > [  102.186312] ata1.01: configured for MWDMA2
> > [  102.187498] ata1.00: device reported invalid CHS sector 0
> > [  102.189078] ata1: EH complete
> > [  132.862149] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
> > [  132.864011] ata1.00: failed command: READ DMA
> > [  132.865674] ata1.00: cmd c8/00:c0:40:22:00/00:00:00:00:00/e0 tag 0 dma 98304 in
> > [  132.865682]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x20 (host bus error)
> > [  132.869786] ata1.00: status: { DRDY }
> > [  137.949377] ata1.00: qc timeout (cmd 0xec)
> > [  137.950632] ata1.00: failed to IDENTIFY (I/O error, err_mask=0x4)
> > [  137.952549] ata1.00: revalidation failed (errno=-5)
> > [  142.954461] ata1: link is slow to respond, please be patient (ready=0)
> > 
> > I've tracked this down to „ata: make ata port as parent device of scsi
> > host“ (9a6d6a2ddabbd32c07f6a38b659e5f3db319fa5a) with git biset.
> > 
> >     ata: make ata port as parent device of scsi host
> >     
> >     Currently, the device tree of ata port and scsi host looks as below,
> >     
> >             /sys/devices/pci0000:00/0000:00:1f.2    (ahci controller)
> >             |-- ata1                                (ata port)
> >             |-- host0                               (scsi host)
> >                |-- target0:0:0                      (scsi target)
> >                    |-- 0:0:0:0                      (disk)
> >     
> >     This patch makes ata port as parent device of scsi host, then it becomes
> >     
> >             /sys/devices/pci0000:00/0000:00:1f.2    (ahci controller)
> >             |-- ata1                                (ata port)
> >                 |-- host0                           (scsi host)
> >                     |-- target0:0:0                 (scsi target)
> >                         |-- 0:0:0:0                 (disk)
> >     
> >     With this change, the ata port runtime PM is easier.
> >     For example, the ata port runtime suspend will happen as,
> >     
> >     disk suspend --> scsi target suspend --> scsi host suspend --> ata port
> >     suspend.
> >     
> >     Acked-by: Tejun Heo <tj@kernel.org>
> >     Signed-off-by: Lin Ming <ming.m.lin@intel.com>
> >     Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
> > 
> > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> > index 2a5412e..7ae1e77 100644
> > --- a/drivers/ata/libata-scsi.c
> > +++ b/drivers/ata/libata-scsi.c
> > @@ -3398,7 +3398,7 @@ int ata_scsi_add_hosts(struct ata_host *host, struct scsi_host_template *sht)
> >                  */
> >                 shost->max_host_blocked = 1;
> >  
> > -               rc = scsi_add_host(ap->scsi_host, ap->host->dev);
> > +               rc = scsi_add_host(ap->scsi_host, &ap->tdev);
> >                 if (rc)
> >                         goto err_add;
> >         }
> > 
> > Can you tell, what might be wrong?
> > 
> > % cat /proc/cpuinfo
> > processor	: 0
> > cpu		: 7455, altivec supported
> > clock		: 798.720000MHz
> > revision	: 3.3 (pvr 8001 0303)
> > bogomips	: 48.58
> > timebase	: 18432000
> > platform	: PowerMac
> > model		: PowerBook6,3
> > machine		: PowerBook6,3
> > motherboard	: PowerBook6,3 MacRISC3 Power Macintosh
> > detected as	: 287 (iBook G4)
> > pmac flags	: 0000001b
> > L2 cache	: 256K unified
> > pmac-generation	: NewWorld
> > Memory		: 640 MB
> > 
> > # qemu-system-ppc -enable-kvm -M mac99 -cpu G4 -k de \
> >   -kernel /boot/vmlinuz-3.3.0-rc5 \
> >   -append 'root=/dev/sda ro console=ttyPZ0 zcache' \
> >   -hda /mnt/data/debian-base-root.raw -hdb /mnt/data/debian-base-var.raw
> > 
> > Bye, Jörg.
> 


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Jörg Sommer - March 15, 2012, 7:48 a.m.
Lin Ming hat am Thu 15. Mar, 11:26 (+0800) geschrieben:
> On Thu, 2012-03-15 at 09:59 +0800, Lin Ming wrote:
> > On Thu, 2012-03-15 at 02:48 +0100, Jörg Sommer wrote:
> > > Hi,
> > > 
> > > I'm getting these messages in a KVM virtualized host and the access to
> > > the disks is very slow. Using libata.dma=0 suppresses the warnings, but
> > > the disks are still slow.
> > 
> > Hi Jörg,
> > 
> > Let me try to reproduce this issue first.
> 
> I tried below commands on x86_32, but can't reproduce it.
> 
> qemu-system-i386 -kernel /root/vmlinuz-3.3.0-rc7 -append "root=/dev/sda1
> zcache" -hda /root/debian-32.img -hdb /root/data.img
> 
> Maybe because i386 uses different ata controller than ppc(ata_piix vs
> pata-macio).
> 
> I'll try qemu-system-ppc.
> 
> Did you need to run some workload to trigger these warings?
> Or did you get these warnings right after booting the VM?

These warnings come up before »INIT started«. I don't have to do
anything, just wait and see.

# truncate -s100M /mnt/data/new
# mke2fs -Fq /mnt/data/new
# mount -o loop /mnt/data/new /mnt/other
# cp --parents /bin/zsh-static /mnt/other/zsh
# umount /mnt/other
# qemu-system-ppc -enable-kvm -M mac99 -cpu G4 -k de -kernel /boot/vmlinuz-3.3.0-rc5-04520-g8d233c0 -append 'root=/dev/sda ro console=ttyPZ0 init=/zsh' -hda /mnt/data/new

I've uploaded my config and the kernel:
http://alioth.debian.org/~jo-guest/config-3.3.0-rc5-04520-g8d233c0
http://alioth.debian.org/~jo-guest/vmlinuz-3.3.0-rc5-04520-g8d233c0

You have to switch to the serial console (Ctrl-Alt-3 or with -nographic
Ctrl-a c). All kernel messages arrive there.

> Would you please try to disable ata port runtime pm?
> You can disable it by, for example,

Is this also possible with a kernel parameter? It takes very long until I
get a shell prompt.

Bye, Jörg.

Patch

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 2a5412e..7ae1e77 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3398,7 +3398,7 @@  int ata_scsi_add_hosts(struct ata_host *host, struct scsi_host_template *sht)
                 */
                shost->max_host_blocked = 1;
 
-               rc = scsi_add_host(ap->scsi_host, ap->host->dev);
+               rc = scsi_add_host(ap->scsi_host, &ap->tdev);
                if (rc)
                        goto err_add;
        }