Re: [Qemu-devel] [PATCH] boot: fix path pattern of scsi device

[Paolo Bonzini <pbonzini@redhat.com>]

Il 28/05/2013 11:35, Amos Kong ha scritto:
> On Tue, May 28, 2013 at 10:06:51AM +0200, Paolo Bonzini wrote:
>> Il 28/05/2013 09:40, Amos Kong ha scritto:
>>> bootindex parameter of scsi device doesn't work, it causes
>>> by wrong pattern in seabios.
>>>
>>> qemu passes the following firmware dev_path to seabios:
>>>  /pci@i0cf8/scsi@4/virtio-scsi-device/channel@0/disk@0,0
>>
>> No, this is another unexpected change due to the virtio refactoring in
>> QEMU.  The right fix is in QEMU, by adding a get_fw_dev_path
>> implementation in hw/virtio/virtio-bus.c.
> 
> Hi Paolo,
> 
> We could not fix this by implementing get_fw_dev_path in
> hw/virtio/virtio-bus.c
> 
> virtio-bus is the parent bus of scsi-bus, scsibus_get_fw_dev_path()
> will be called after called virtio_bus_get_fw_dev_path().
> 
> str0 = returns of parents of virtio-bus  /* eg: /pci@i0cf8/scsi@4  */
> str1 = return of virtio_bus_get_fw_dev_path() /* eg: .. */
> str2 = scsibus_get_fw_dev_path() /* eg: channel@0/disk@0,0 */
> 
> The final fw_dev_path should be $str0/$str1/$str2
> 
> | static int qdev_get_fw_dev_path_helper(DeviceState *dev, char *p, int size)
> | {
> |     int l = 0;
> | 
> |     if (dev && dev->parent_bus) {
> |         char *d;
> |         l = qdev_get_fw_dev_path_helper(dev->parent_bus->parent, p, size);
> |         d = bus_get_fw_dev_path(dev->parent_bus, dev);
> |         if (d) {
> |             l += snprintf(p + l, size - l, "%s", d);
> |             g_free(d);
> 
> if we implement virtio_bus_get_fw_dev_path(), the return value will be set to $str1
> 
> |         } else {
> |             l += snprintf(p + l, size - l, "%s", object_get_typename(OBJECT(dev)));
> 
> Currently we didn't implement virtio_bus_get_fw_dev_path(), so 'virtio-scsi-device' was set to $str1
> 
> |         }
> |  
> 
> However, we need to change the pattern.

Turn this:

            l += snprintf(p + l, size - l, "%s", object_get_typename(OBJECT(dev)));

into the default implementation of get_fw_dev_path (in TYPE_BUS),
and change qdev_get_fw_dev_path_helper to

        if (d) {
            l += snprintf(p + l, size - l, "%s", d);
            g_free(d);
        } else {
            return l;
        }

Then virtio_bus_get_fw_dev_path can just return NULL.

Paolo

> Amos.
> 
>> We fixed it already for migration paths, it should be easy to do the
>> same for this.
>>
>> Please Cc qemu-stable@nongnu.org when sending the QEMU patch.
>>
>> Thanks,
>>
>> Paolo
>>
>>> Signed-off-by: Amos Kong <akong@redhat.com>
>>> ---
>>>  src/boot.c | 5 +++--
>>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/src/boot.c b/src/boot.c
>>> index c308602..cd9d784 100644
>>> --- a/src/boot.c
>>> +++ b/src/boot.c
>>> @@ -138,10 +138,11 @@ int bootprio_find_scsi_device(struct pci_device *pci, int target, int lun)
>>>      if (!pci)
>>>          // support only pci machine for now
>>>          return -1;
>>> -    // Find scsi drive - for example: /pci@i0cf8/scsi@5/channel@0/disk@1,0
>>> +    /* Find scsi drive - for example:
>>> +       /pci@i0cf8/scsi@5/virtio-scsi-device/channel@0/disk@1,0 */
>>>      char desc[256], *p;
>>>      p = build_pci_path(desc, sizeof(desc), "*", pci);
>>> -    snprintf(p, desc+sizeof(desc)-p, "/*@0/*@%d,%d", target, lun);
>>> +    snprintf(p, desc+sizeof(desc)-p, "/*/*@0/*@%d,%d", target, lun);
>>>      return find_prio(desc);
>>>  }
>>>  
>>>