[Libguestfs] [PATCH 4/3] Add API to query the core kernel arguments

[Daniel P. Berrange]

Add an API which allows querying of the core kernel arguments
required for the appliance kernel/initrd.

  ><fs> get-kernel-args
  panic=1 console=ttyS0 udevtimeout=300 noapic acpi=off printk.time=1 cgroup_disable=memory

This does not include the vmchannel configuration parameter,
nor optional args such as selinux, or verbosity setting.
---
 src/generator.ml |   10 ++++++++++
 src/guestfs.c    |   27 +++++++++++++++++----------
 2 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/src/generator.ml b/src/generator.ml
index 41f8014..79619d7 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -689,6 +689,16 @@ Return the current appliance initrd path.
 This is NULL if the initrd has not yet been located,
 otherwise it returns the initrd path.");
 
+  ("get_kernel_args", (RConstString "append", []), -1, [],
+   [InitNone, Always, TestRun (
+      [["get_kernel_args"]])],
+   "get the appliance kernel arguments",
+   "\
+Return the basic appliance kernel arguments
+
+This returns the basic appliance kernel arguments
+without the guestfwd configuration parameter");
+
   ("set_path", (RErr, [OptString "searchpath"]), -1, [FishAlias "path"],
    [],
    "set the search path",
diff --git a/src/guestfs.c b/src/guestfs.c
index 850dc9a..1463e1a 100644
--- a/src/guestfs.c
+++ b/src/guestfs.c
@@ -675,6 +675,21 @@ guestfs__get_initrd (guestfs_h *g)
   return g->initrd;
 }
 
+const char *
+guestfs__get_kernel_args (guestfs_h *g)
+{
+#define LINUX_CMDLINE							\
+    "panic=1 "         /* force kernel to panic if daemon exits */	\
+    "console=ttyS0 "   /* serial console */				\
+    "udevtimeout=300 " /* good for very slow systems (RHBZ#480319) */	\
+    "noapic "          /* workaround for RHBZ#502058 - ok if not SMP */ \
+    "acpi=off "        /* we don't need ACPI, turn it off */		\
+    "printk.time=1 "   /* display timestamp before kernel messages */   \
+    "cgroup_disable=memory " /* saves us about 5 MB of RAM */
+
+    return LINUX_CMDLINE;
+}
+
 int
 guestfs__set_qemu (guestfs_h *g, const char *qemu)
 {
@@ -1475,23 +1490,15 @@ guestfs__launch_spawn (guestfs_h *g)
     add_cmdline (g, "-net");
     add_cmdline (g, "nic,model=" NET_IF ",vlan=0");
 
-#define LINUX_CMDLINE							\
-    "panic=1 "         /* force kernel to panic if daemon exits */	\
-    "console=ttyS0 "   /* serial console */				\
-    "udevtimeout=300 " /* good for very slow systems (RHBZ#480319) */	\
-    "noapic "          /* workaround for RHBZ#502058 - ok if not SMP */ \
-    "acpi=off "        /* we don't need ACPI, turn it off */		\
-    "printk.time=1 "   /* display timestamp before kernel messages */   \
-    "cgroup_disable=memory " /* saves us about 5 MB of RAM */
-
     /* Linux kernel command line. */
     snprintf (buf, sizeof buf,
-              LINUX_CMDLINE
+	      "%s "             /* Basic command line */
               "%s "             /* (selinux) */
               "%s "             /* (vmchannel) */
               "%s "             /* (verbose) */
               "TERM=%s "        /* (TERM environment variable) */
               "%s",             /* (append) */
+	      guestfs__get_kernel_args (g),
               g->selinux ? "selinux=1 enforcing=0" : "selinux=0",
               vmchannel ? vmchannel : "",
               g->verbose ? "guestfs_verbose=1" : "",
-- 
1.6.6.1