Re: [Xen-devel] [PATCH] qemu-xen: read default pci passthrough values

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 3 Feb 2011, Ian Jackson wrote:
> Stefano Stabellini writes ("[Xen-devel] [PATCH] qemu-xen: read default pci 
> passthrough values"):
> > If there are no devices assigned to the domain at boot, we don't read
> > the default pci passthrough parameters.
> > This patch fixes it.
> 
> The semantics you intend seem sensible, but:
> 
> The variable "num" seems completely unused after we went to all the
> effort of reading num_devs to get it.  The code seems to read
> .../num_devs just to check that the key exists, and doesn't mind "0"
> as an answer.  With your patch applied, we don't even care whether the
> key exists.
> 
> So why do we bother reading .../num_devs and converting it to an
> integer and assigning it to nums ?

That is a very good point. Reading num_devs is completely useless hence
I am removing it.

---


diff --git a/xenstore.c b/xenstore.c
index d364a5e..eed4955 100644
--- a/xenstore.c
+++ b/xenstore.c
@@ -731,18 +731,7 @@ void xenstore_parse_domain_config(int hvm_domid)
      * hvm_domid is always equal to domid */
     hvm_domid = domid;
 
-    /* get the pci pass-through parameter */
-    if (pasprintf(&buf, "/local/domain/0/backend/pci/%u/%u/num_devs",
-                  hvm_domid, pci_devid) == -1)
-        goto out;
-
-    free(params);
-    params = xs_read(xsh, XBT_NULL, buf, &len);
-    if (params == NULL)
-        goto out;
-    num = atoi(params);
-
-    /* get the pci pass-through parameter */
+    /* get the pci pass-through parameters */
     if (pasprintf(&buf, "/local/domain/0/backend/pci/%u/%u/msitranslate",
                   hvm_domid, pci_devid) != -1)
     {

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