[libvirt] [PATCH] Prefer to use 'qemu-system-i386' over 'qemu'

[Daniel P. Berrange]

From: "Daniel P. Berrange" <berrange at redhat.com>

For i686 arch we look for the 'qemu' binary, followed by the
'qemu-system-x86_64' binary. This is not good with QEMU 1.0,
since the 'qemu' binary was renamed to 'qemu-system-i386'
and the 'qemu' name might be reused for another purpose
later.

Make sure we look for 'qemu-system-i386', then 'qemu-system-x86_64'
then the qemu-kvm binary. Only use 'qemu' as a very last resort

* src/qemu/qemu_capabilities.c: Prefer qemu-system-i386
---
 src/qemu/qemu_capabilities.c |   48 ++++++++++++++++++++++++-----------------
 1 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 0e09d6d..16d9b21 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -169,7 +169,6 @@ struct qemu_arch_info {
     int wordsize;
     const char *machine;
     const char *binary;
-    const char *altbinary;
     const struct qemu_feature_flags *flags;
     int nflags;
 };
@@ -189,25 +188,25 @@ static const struct qemu_feature_flags const arch_info_x86_64_flags [] = {
 
 /* The archicture tables for supported QEMU archs */
 static const struct qemu_arch_info const arch_info_hvm[] = {
-    {  "i686",   32, NULL, "qemu",
-       "qemu-system-x86_64", arch_info_i686_flags, 4 },
+    {  "i686", 32, NULL, "qemu-system-i386",
+       arch_info_i686_flags, 4 },
     {  "x86_64", 64, NULL, "qemu-system-x86_64",
-       NULL, arch_info_x86_64_flags, 2 },
-    {  "arm",    32, NULL, "qemu-system-arm",    NULL, NULL, 0 },
-    {  "microblaze", 32, NULL, "qemu-system-microblaze",   NULL, NULL, 0 },
-    {  "microblazeel", 32, NULL, "qemu-system-microblazeel",   NULL, NULL, 0 },
-    {  "mips",   32, NULL, "qemu-system-mips",   NULL, NULL, 0 },
-    {  "mipsel", 32, NULL, "qemu-system-mipsel", NULL, NULL, 0 },
-    {  "sparc",  32, NULL, "qemu-system-sparc",  NULL, NULL, 0 },
-    {  "ppc",    32, NULL, "qemu-system-ppc",    NULL, NULL, 0 },
-    {  "ppc64",    64, NULL, "qemu-system-ppc64",    NULL, NULL, 0 },
-    {  "itanium", 64, NULL, "qemu-system-ia64",  NULL, NULL, 0 },
-    {  "s390x",  64, NULL, "qemu-system-s390x",  NULL, NULL, 0 },
+       arch_info_x86_64_flags, 2 },
+    {  "arm", 32, NULL, "qemu-system-arm",  NULL, 0 },
+    {  "microblaze", 32, NULL, "qemu-system-microblaze", NULL, 0 },
+    {  "microblazeel", 32, NULL, "qemu-system-microblazeel", NULL, 0 },
+    {  "mips", 32, NULL, "qemu-system-mips", NULL, 0 },
+    {  "mipsel", 32, NULL, "qemu-system-mipsel", NULL, 0 },
+    {  "sparc", 32, NULL, "qemu-system-sparc", NULL, 0 },
+    {  "ppc", 32, NULL, "qemu-system-ppc", NULL, 0 },
+    {  "ppc64", 64, NULL, "qemu-system-ppc64", NULL, 0 },
+    {  "itanium", 64, NULL, "qemu-system-ia64", NULL, 0 },
+    {  "s390x",  64, NULL, "qemu-system-s390x", NULL, 0 },
 };
 
 static const struct qemu_arch_info const arch_info_xen[] = {
-    {  "i686",   32, "xenner", "xenner", NULL, arch_info_i686_flags, 4 },
-    {  "x86_64", 64, "xenner", "xenner", NULL, arch_info_x86_64_flags, 2 },
+    {  "i686",   32, "xenner", "xenner", arch_info_i686_flags, 4 },
+    {  "x86_64", 64, "xenner", "xenner", arch_info_x86_64_flags, 2 },
 };
 
 
@@ -643,10 +642,11 @@ qemuCapsInitGuest(virCapsPtr caps,
      */
     binary = virFindFileInPath(info->binary);
 
-    if (binary == NULL || !virFileIsExecutable(binary)) {
-        VIR_FREE(binary);
-        binary = virFindFileInPath(info->altbinary);
-    }
+    /* If i386 binary is missing, we can trivially
+     * replace it with a qemu-system-x86_64 binary
+     */
+    if (binary == NULL && STREQ(info->binary, "qemu-system-i386"))
+        binary = virFindFileInPath("qemu-system-x86_64");
 
     /* Can use acceleration for KVM/KQEMU if
      *  - host & guest arches match
@@ -668,6 +668,10 @@ qemuCapsInitGuest(virCapsPtr caps,
                     continue;
 
                 haskvm = 1;
+
+                /* We can use the KVM binary for the TCG case too
+                 * (probably)
+                 */
                 if (!binary)
                     binary = kvmbin;
 
@@ -679,6 +683,10 @@ qemuCapsInitGuest(virCapsPtr caps,
             haskqemu = 1;
     }
 
+    /* Another fallback for i386, try the old name now */
+    if (binary == NULL && STREQ(info->binary, "qemu-system-i386"))
+        binary = virFindFileInPath("qemu");
+
     if (!binary)
         return 0;
 
-- 
1.7.7.6