[Xen-devel] [PATCH 3/5] libxl: Add function to determine device model type

[Jim Fehlig <jfehlig@xxxxxxxx>]

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@xxxxxxxx>
---
 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,
-- 
1.8.4.5


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