[libvirt] [PATCH 3/5] libxl: Add function to determine device model type

[Michal Privoznik]

On 19.09.2014 21:23, Jim Fehlig wrote:
> This patch introduces a function to detect whether the specified
> emulator is QEMU_XEN or QEMU_XEN_TRADITIONAL.  Detection is based on the
> string "Options specific to the Xen version:" in '$qemu -help' output.
> AFAIK, the only qemu containing that string in help output is the
> old Xen fork (aka qemu-dm).
>
> Note:
> QEMU_XEN means a qemu that contains support for Xen.
>
> QEMU_XEN_TRADITIONAL means Xen's old forked qemu 0.10.2
>
> Signed-off-by: Jim Fehlig <jfehlig at suse.com>
> ---
>   src/libxl/libxl_conf.c | 32 ++++++++++++++++++++++++++++++++
>   src/libxl/libxl_conf.h |  3 +++
>   2 files changed, 35 insertions(+)
>
> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
> index 0a781f9..ff3f6b5 100644
> --- a/src/libxl/libxl_conf.c
> +++ b/src/libxl/libxl_conf.c
> @@ -40,6 +40,7 @@
>   #include "viralloc.h"
>   #include "viruuid.h"
>   #include "capabilities.h"
> +#include "vircommand.h"
>   #include "libxl_domain.h"
>   #include "libxl_conf.h"
>   #include "libxl_utils.h"
> @@ -796,6 +797,37 @@ libxlDiskSetDiscard(libxl_device_disk *x_disk, int discard)
>   }
>
>
> +#define LIBXL_QEMU_DM_STR  "Options specific to the Xen version:"
> +
> +int
> +libxlDomainGetEmulatorType(const virDomainDef *def)
> +{
> +    int ret = LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN;
> +    virCommandPtr cmd = NULL;
> +    char *output = NULL;
> +
> +    if (STREQ(def->os.type, "hvm")) {
> +        if (def->emulator) {
> +            cmd = virCommandNew(def->emulator);
> +
> +            virCommandAddArgList(cmd, "-help", NULL);
> +            virCommandSetOutputBuffer(cmd, &output);
> +
> +            if (virCommandRun(cmd, NULL) < 0)
> +                goto cleanup;
> +
> +            if (strstr(output, LIBXL_QEMU_DM_STR))
> +                ret = LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
> +        }
> +    }
> +
> + cleanup:
> +    VIR_FREE(output);
> +    virCommandFree(cmd);
> +    return ret;
> +}
> +
> +
>   int
>   libxlMakeDisk(virDomainDiskDefPtr l_disk, libxl_device_disk *x_disk)
>   {
> diff --git a/src/libxl/libxl_conf.h b/src/libxl/libxl_conf.h
> index da66b4e..25f77ea 100644
> --- a/src/libxl/libxl_conf.h
> +++ b/src/libxl/libxl_conf.h
> @@ -163,6 +163,9 @@ virCapsPtr
>   libxlMakeCapabilities(libxl_ctx *ctx);
>
>   int
> +libxlDomainGetEmulatorType(const virDomainDef *def);
> +
> +int
>   libxlMakeDisk(virDomainDiskDefPtr l_dev, libxl_device_disk *x_dev);
>   int
>   libxlMakeNic(virDomainDefPtr def,
>

Well, we've tried hard to move away from parsing 'qemu -help' output. 
But on the other hand, this is trivial compared to virQEMUCaps code 
we've developed. So I'd give green flag to this.

Michal