Re: [Qemu-devel] [PATCH 4/7] scsi-disk: introduce dma_readv and dma_writev

[xiaoqiang zhao <zxq_yx_007@163.com>]

在 2016年06月03日 13:22, Mark Cave-Ayland 写道:
> On 03/06/16 03:56, xiaoqiang zhao wrote:
>
>> 在 2016年06月02日 03:07, Mark Cave-Ayland 写道:
>>> On 23/05/16 13:54, Paolo Bonzini wrote:
>>>
>>>>> These are replacements for blk_aio_preadv and blk_aio_pwritev that
>>>> allow
>>>>> customization of the data path.  They reuse the DMA helpers' DMAIOFunc
>>>>> callback type, so that the same function can be used in either the
>>>>> QEMUSGList or the bounce-buffered case.
>>>>>
>>>>> This customization will be needed in the next patch to do zero-copy
>>>>> SG_IO on scsi-block.
>>>>>
>>>>> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
>>>>> ---
>>>>>   hw/scsi/scsi-disk.c | 63
>>>> +++++++++++++++++++++++++++++++++++++++++++----------
>>>>>   1 file changed, 52 insertions(+), 11 deletions(-)
>>>>>
>>> Hi Paolo,
>>>
>>> This patch appears to break qemu-system-sparc booting from CDROM with
>>> the following command line:
>>>
>>> ./qemu-system-sparc -cdrom debian-40r4a-sparc-netinst.iso -boot d
>>>
>>> Instead of booting straight into SILO, OpenBIOS hangs when trying to
>>> read from the CDROM device.
>> Paolo:
>>    By using git bisect on master branch , I found this patch also break
>> qemu-system-arm from booting.
>>    command line:
>>   qemu-system-arm -M versatilepb -kernel vmlinuz-3.2.0-4-versatile
>> -initrd initrd.img-3.2.0-4-versatile -hda
>> /home/hitmoon/debian_wheezy_armel_standard.qcow2 -append 'root=/dev/sda1'
>>
>>   The booting process stops at mounting the root partition and after
>> timeout droped into a initramfs shell. The device '/dev/sda1' is
>> presented . I guess it can not read properly from sda1.
> I've just sent through a patch which fixes the issue for me - please
> test and report back!
>
> Paolo - not sure if it's worth a follow-up patch that renames the
> relevant _readv/_writev functions in scsi-disk.c to _preadv/_pwritev to
> try and help avoid such confusion in future?
>
>
> ATB,
>
> Mark.
>
>
Mark:
   I can confirm it works for me !