[libvirt] [PATCH] Don't list capabilities entries if emulators can't be accessed

[Daniel P. Berrange]

On Wed, Aug 20, 2008 at 12:51:05PM -0400, Cole Robinson wrote:
> The patch below fixes capabilities xml generation for
> the qemu driver if the emulators aren't found in the
> hardcoded paths. Current behavior will add a <guest>
> entry for the emulator even if it does not exist, patch
> fixes this to check that we actually have access.
> 
> This brings up another issue, that hardcoded paths
> aren't exactly distro friendly. I'm not really familiar
> with what options we have to allow specifying these
> at build time (or something else). Anyone have an
> idea?

Ideally we'd just list the binary names, and search in $PATH for them.
Patches for this welcome...

> diff --git a/src/qemu_conf.c b/src/qemu_conf.c
> index dc9e42a..0328cc1 100644
> --- a/src/qemu_conf.c
> +++ b/src/qemu_conf.c
> @@ -230,6 +230,10 @@ qemudCapsInitGuest(virCapsPtr caps,
>      virCapsGuestPtr guest;
>      int i;
>  
> +    /* Check for existance of base emulator */
> +    if (access(info->binary, X_OK) == -1)
> +        return 0;
> +

This isn't right - this means that if KVM is installed, but QEMU is
not installed you won't get any capabilities.

Basically we need todo all the access() checks for QEMU, KVM, /dev/kvm
up-front. And then generated the capabilites if either QEMU or KVM is
available.

Daniel
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