Re: [PATCH] 2/2: Fall back to plain Qemu if KVM is not present, report errors from libkvm

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Simon Kagstrom wrote:
> This patch implements fall-back to plain Qemu if KVM is not
> present. Some logic has been moved into kvm_qemu_init.
>
> Signed-off-by: Simon Kagstrom <simon.kagstrom-6Uc+yI3S9P8@public.gmane.org>
>
>   
[please inline patches in the future for easier reviewing]

-#if USE_KVM
     phys_ram_size = ram_size + vga_ram_size + bios_size;
+#if USE_KVM
+    /* Initialize kvm */
     if (kvm_allowed) {
-	    phys_ram_size += KVM_EXTRA_PAGES * 4096;
-	    kvm_qemu_init();
-    } else {
-	    phys_ram_base = qemu_vmalloc(phys_ram_size);
-	    if (!phys_ram_base) {
-		    fprintf(stderr, "Could not allocate physical memory\n");
-		    exit(1);
-	    }
+	if (kvm_qemu_init() < 0) {
+	    fprintf(stderr, "Could not initialize KVM\n");
+	    kvm_allowed = 0;
+	}
+    }
+    /* Fall back to normal qemu if KVM fails */
+    if (!kvm_allowed) {
+	phys_ram_base = qemu_vmalloc(phys_ram_size);
+	if (!phys_ram_base) {
+	    fprintf(stderr, "Could not allocate physical memory\n");
+	    exit(1);
+	}
     }
 #else
-    phys_ram_size = ram_size + vga_ram_size + bios_size;



This bit is rather awkward, since it disabled kvm after it has been 
enabled.  It's a cleaner to never enable kvm_allowed in the first place 
(i.e. during argument parsing).

How about a

    int libkvm_init(kvm_libcontext_t *libcontext);
    void libkvm_exit(kvm_libcontext_t libcontext);
   
    int kvm_create(kvm_libcontext_t libcontext, kvm_context_t* vm);
    void kvm_destroy(kvm_context_t *vm);

at present, libkvm_init() can just call access(2) on /dev/kvm.  In the 
future, it is planned that open("/dev/kvm") will not create a VM (it 
just opens a communication channel to the driver), so that libkvm_init() 
will open the device and store the fd.

-- 
error compiling committee.c: too many arguments to function


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