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.