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Date: Thu, 14 Mar 2013 11:00:24 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH V2 WIP 0/2] vhost-scsi: new device
 supporting the tcm_vhost Linux kernel module
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: kvm@vger.kernel.org, Rusty Russell <rusty@rustcorp.com.au>, qemu-devel@nongnu.org, Nicholas Bellinger <nab@linux-iscsi.org>, virtualization@lists.linux-foundation.org, target-devel@vger.kernel.org, Stefan Hajnoczi <stefanha@redhat.com>, Asias He <asias@redhat.com>


>> --------------- 8 ---------------> seabios patch:
>> diff --git a/src/virtio-scsi.c b/src/virtio-scsi.c
>> index 879ddfb..4de1255 100644
>> --- a/src/virtio-scsi.c
>> +++ b/src/virtio-scsi.c
>> @@ -147,6 +147,9 @@ init_virtio_scsi(struct pci_device *pci)
>>          goto fail;
>>      }
>>  
>> +    vp_set_status(ioaddr, VIRTIO_CONFIG_S_ACKNOWLEDGE |
>> +                  VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK);
>> +
>>      int i, tot;
>>      for (tot = 0, i = 0; i < 256; i++)
>>          tot += virtio_scsi_scan_target(pci, ioaddr, vq, i);
>> @@ -154,8 +157,6 @@ init_virtio_scsi(struct pci_device *pci)
>>      if (!tot)
>>          goto fail;
>>  
>> -    vp_set_status(ioaddr, VIRTIO_CONFIG_S_ACKNOWLEDGE |
>> -                  VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK);
>>      return;
>>  
>>  fail:

ACK.

>> diff --git a/src/virtio-scsi.h b/src/virtio-scsi.h
>> index bbfbf30..96c3701 100644
>> --- a/src/virtio-scsi.h
>> +++ b/src/virtio-scsi.h
>> @@ -26,7 +26,7 @@ struct virtio_scsi_req_cmd {
>>      u8 prio;
>>      u8 crn;
>>      char cdb[VIRTIO_SCSI_CDB_SIZE];
>> -};
>> +} __attribute__((packed));
>>  
>>  /* This is the first element of the "in" scatter-gather list. */
>>  struct virtio_scsi_resp_cmd {
>> @@ -36,7 +36,7 @@ struct virtio_scsi_resp_cmd {
>>      u8 status;
>>      u8 response;
>>      u8 sense[VIRTIO_SCSI_SENSE_SIZE];
>> -};
>> +} __attribute__((packed));
>>  
>>  #define VIRTIO_SCSI_S_OK            0
> 
> I see, the padding creates the problem?

Looks like it does for req_cmd (which has length 51 and is padded to
56).  QEMU incorrectly relies on the framing.  Both of these are SeaBIOS
bugs, please do submit the patch.

Paolo