Re: [Qemu-devel] [PULL 18/19] macio: move unaligned DMA write code into separate pmac_dma_write() function

[Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>]

On 01/08/15 13:37, Aurelien Jarno wrote:

> On 2015-08-01 12:21, Mark Cave-Ayland wrote:
>> On 28/07/15 19:02, Aurelien Jarno wrote:
>>
>>>> Thanks for the heads-up. I have a fairly comprehensive suite of various
>>>> OS test images I use for OpenBIOS testing and evidently not a single one
>>>> of them issues a TRIM command as I don't see any regressions here. Can
>>>> you point me towards the particular test image you are using?
>>>
>>> You need a Linux based image, with a relatively recent kernel (3.2 is
>>> ok). The disk image has to be created with -drive file=...,discard=unmap
>>> for the TRIM feature to be advertised in the guest. Finally you need to
>>> run the command "fstrim /" or mount a partition or the swap with the
>>> option discard.
>>>
>>> As a summary:
>>> - wget https://people.debian.org/~aurel32/qemu/powerpc/debian_wheezy_powerpc_standard.qcow2
>>> - qemu-system-ppc -snapshot -drive file=debian_wheezy_powerpc_standard.qcow2,discard=unmap 
>>> - in the image, login as root (password root) and run fstrim /.
>>>
>>> I have looked a bit at the code, and it looks like we have to provide a
>>> function similar to pmac_dma_read/write for the TRIM. I'll look at it a
>>> bit more in details and I will try to provide a patch, but it's probably
>>> won't be before the week-end.
>>
>> I should add that regardless of whether the TRIM patch is applied or
>> not, the wheezy image reports DMA timeout errors which I don't see in
>> the squeeze or lenny images:
>>
>>
>> [    5.420949] ata2.00: configured for MWDMA2
>> [    5.451070] rtc-generic rtc-generic: setting system clock to
>> 2015-08-01 11:13:25 UTC (1438427605)
>> [    5.461100] Initializing network drop monitor service
>> [    5.480460] scsi 1:0:0:0: CD-ROM            QEMU     QEMU DVD-ROM
>>  2.3. PQ: 0 ANSI: 5
>> [    5.540013] Freeing unused kernel memory: 244k freed
>> [    6.677779] udevd[46]: starting version 175
>> [    8.548044] ne2k-pci.c:v1.03 9/22/2003 D. Becker/P. Gortmaker
>> [    8.761179] eth0: RealTek RTL-8029 found at 0x400, IRQ 23,
>> 52:54:00:12:34:56.
>> [   10.300003] sd 0:0:0:0: [sda] 52428800 512-byte logical blocks: (26.8
>> GB/25.0 GiB)
>> [   10.359219] pata-macio 0.00021000:ata-4: timeout flushing DMA
>> [   10.400935] ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
>> [   10.412768] ata2.00: BMDMA stat 0x6
>> [   10.421732] sr 1:0:0:0: CDB: Mode Sense(10): 5a 00 2a 00 00 00 00 00
>> 80 00
>> [   10.430301] ata2.00: cmd a0/01:00:00:80:00/00:00:00:00:00/a0 tag 0
>> dma 16512 in
>> [   10.430334]          res 50/00:03:00:80:00/00:00:00:00:00/a0 Emask
>> 0x20 (host bus error)
>> [   10.459348] ata2.00: status: { DRDY }
>> [   10.516892] sd 0:0:0:0: [sda] Write Protect is off
>> [   10.524614] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
>> [   10.545353] sd 0:0:0:0: [sda] Write cache: enabled, read cache:
>> enabled, doesn't support DPO or FUA
>> [   10.655885] ata2.00: configured for MWDMA2
>> [   10.665041] ata2: EH complete
>>
>> and:
>>
>> [   14.016326] PM: Hibernation image partition 8:4 present
>> [   14.016380] PM: Looking for hibernation image.
>> [   14.020555] PM: Image not found (code -22)
>> [   14.020642] PM: Hibernation image not present or could not be loaded.
>> [   14.513667] EXT4-fs (sda3): mounted filesystem with ordered data
>> mode. Opts: (null)
>> [   24.750778] udevd[252]: starting version 175
>> [   31.040517] pata-macio 0.00021000:ata-4: timeout flushing DMA
>> [   31.528077] ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
>> [   31.546115] ata2.00: BMDMA stat 0x6
>> [   31.562905] sr 1:0:0:0: [sr0] CDB: Get configuration: 46 00 00 00 00
>> 00 00 00 10 00
>> [   31.572557] ata2.00: cmd a0/01:00:00:10:00/00:00:00:00:00/a0 tag 0
>> dma 16400 in
>> [   31.572589]          res 50/00:03:00:10:00/00:00:00:00:00/a0 Emask
>> 0x20 (host bus error)
>> [   31.597940] ata2.00: status: { DRDY }
>> [   32.139342] ata2.00: configured for MWDMA2
>> [   32.148769] ata2: EH complete
>>
>>
>> I'll have a quick look with debugging enabled to see if I can spot
>> anything obvious.
> 
> ata2.00 is actually the CD-ROM drive. I have the same issue there,
> except here, and there are even more messages when mounting the drive.
> That said, it seems to work correctly anyway.

I've worked out what is going on here (it's the non-block transfers) and
have a fix that looks good on my test images here. John/Aurelien, please
can you test on your setups to make sure that everything still works for
you?


ATB,

Mark.