Libguestfs - May 2016 - [PATCH 0/2] Use -bios bios-fast.bin where supported.

NOTE: Not for upstream, yet.

This depends on 3 non-upstream patches.

 - The qemu rework in libguestfs, which in turn depends on what
   Pino is up to.

 - Support for '-L ?' in qemu:
   https://lists.gnu.org/archive/html/qemu-devel/2016-05/threads.html#02596

 - Support for bios-fast.bin in qemu:
   https://lists.gnu.org/archive/html/qemu-devel/2016-05/threads.html#02408

This commit uses -bios bios-fast.bin if available, which basically
stops SeaBIOS from trying to do PCI probing during boot, which is a
waste of time when using the -kernel option.

Rich.

This has to read the data dirs from qemu using the new 'qemu -L ?'
flag added in qemu 2.7.
---
 src/guestfs-internal.h |  1 +
 src/qemu.c             | 81 +++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 78 insertions(+), 4 deletions(-)

diff --git a/src/guestfs-internal.h b/src/guestfs-internal.h
index d325f50..7904a9f 100644
--- a/src/guestfs-internal.h
+++ b/src/guestfs-internal.h
@@ -915,6 +915,7 @@ extern struct qemu_data *guestfs_int_test_qemu (guestfs_h
*g);
 extern struct qemu_data *guestfs_int_init_qemu_version (guestfs_h *g, unsigned
long qemu_version);
 extern int guestfs_int_qemu_supports (guestfs_h *g, const struct qemu_data *,
const char *option);
 extern int guestfs_int_qemu_supports_device (guestfs_h *g, const struct
qemu_data *, const char *device_name);
+extern int guestfs_int_qemu_supports_bios (guestfs_h *g, const struct qemu_data
*, const char *bios_name);
 extern int guestfs_int_qemu_supports_virtio_scsi (guestfs_h *g, struct
qemu_data *);
 extern bool guestfs_int_qemu_version_le (const struct qemu_data *, int
max_major, int max_minor);
 extern bool guestfs_int_qemu_version_ge (const struct qemu_data *, int
min_major, int min_minor);
diff --git a/src/qemu.c b/src/qemu.c
index 259a6fd..0107160 100644
--- a/src/qemu.c
+++ b/src/qemu.c
@@ -50,6 +50,7 @@ COMPILE_REGEXP (re_major_minor, "(\\d+)\\.(\\d+)",
0)
 struct qemu_data {
   char *qemu_help;            /* Output of qemu -help. */
   char *qemu_devices;         /* Output of qemu -device ? */
+  char *qemu_datadirs;        /* Output of qemu -L ? (NULL if not supported) */
 
   /* qemu version (0, 0 if unable to parse). */
   int qemu_version_major, qemu_version_minor;
@@ -71,8 +72,9 @@ static void read_all (guestfs_h *g, void *retv, const char
*buf, size_t len);
 
 /**
  * Test qemu binary (or wrapper) runs, and do C<qemu -help> so we know
- * the version of qemu what options this qemu supports, and
- * C<qemu -device ?> so we know what devices are available.
+ * the version of qemu what options this qemu supports,
+ * C<qemu -device ?> so we know what devices are available,
+ * and C<qemu -L ?> to list data directories.
  *
  * This caches the results in the cachedir so that as long as the qemu
  * binary does not change, calling this is effectively free.
@@ -83,7 +85,8 @@ guestfs_int_test_qemu (guestfs_h *g)
   struct qemu_data *data;
   struct stat statbuf;
   CLEANUP_FREE char *cachedir = NULL, *qemu_stat_filename = NULL,
-    *qemu_help_filename = NULL, *qemu_devices_filename = NULL;
+    *qemu_help_filename = NULL, *qemu_devices_filename = NULL,
+    *qemu_datadirs_filename = NULL;
   FILE *fp;
   int generation;
   uint64_t prev_size, prev_mtime;
@@ -100,6 +103,7 @@ guestfs_int_test_qemu (guestfs_h *g)
   qemu_stat_filename = safe_asprintf (g, "%s/qemu.stat", cachedir);
   qemu_help_filename = safe_asprintf (g, "%s/qemu.help", cachedir);
   qemu_devices_filename = safe_asprintf (g, "%s/qemu.devices",
cachedir);
+  qemu_datadirs_filename = safe_asprintf (g, "%s/qemu.datadirs",
cachedir);
 
   /* Did we previously test the same version of qemu? */
   debug (g, "checking for previously cached test results of %s, in
%s",
@@ -122,7 +126,8 @@ guestfs_int_test_qemu (guestfs_h *g)
      * and qemu -devices ? output.
      */
     if (access (qemu_help_filename, R_OK) == -1 ||
-        access (qemu_devices_filename, R_OK) == -1)
+        access (qemu_devices_filename, R_OK) == -1 ||
+        access (qemu_datadirs_filename, R_OK) == -1)
       goto do_test;
 
     debug (g, "loading previously cached test results");
@@ -143,6 +148,12 @@ guestfs_int_test_qemu (guestfs_h *g)
       return NULL;
     }
 
+    if (guestfs_int_read_whole_file (g, qemu_datadirs_filename,
+                                     &data->qemu_datadirs, NULL) == -1)
{
+      guestfs_int_free_qemu_data (data);
+      return NULL;
+    }
+
     return data;
   }
 
@@ -183,6 +194,19 @@ guestfs_int_test_qemu (guestfs_h *g)
   if (fclose (fp) == -1)
     goto devices_error;
 
+  fp = fopen (qemu_datadirs_filename, "w");
+  if (fp == NULL) {
+  datadirs_error:
+    perrorf (g, "%s", qemu_datadirs_filename);
+    if (fp != NULL) fclose (fp);
+    guestfs_int_free_qemu_data (data);
+    return NULL;
+  }
+  if (fprintf (fp, "%s", data->qemu_datadirs) == -1)
+    goto datadirs_error;
+  if (fclose (fp) == -1)
+    goto datadirs_error;
+
   /* Write the qemu.stat file last so that its presence indicates that
    * the qemu.help and qemu.devices files ought to exist.
    */
@@ -214,6 +238,7 @@ test_qemu (guestfs_h *g, struct qemu_data *data)
 {
   CLEANUP_CMD_CLOSE struct command *cmd1 = guestfs_int_new_command (g);
   CLEANUP_CMD_CLOSE struct command *cmd2 = guestfs_int_new_command (g);
+  CLEANUP_CMD_CLOSE struct command *cmd3 = guestfs_int_new_command (g);
   int r;
 
   guestfs_int_cmd_add_arg (cmd1, g->hv);
@@ -247,6 +272,28 @@ test_qemu (guestfs_h *g, struct qemu_data *data)
   if (r == -1 || !WIFEXITED (r) || WEXITSTATUS (r) != 0)
     goto error;
 
+  /* qemu -L ? only supported in qemu >= 2.7 */
+  if (guestfs_int_qemu_version_ge (data, 2, 7)) {
+    guestfs_int_cmd_add_arg (cmd3, g->hv);
+    guestfs_int_cmd_add_arg (cmd3, "-display");
+    guestfs_int_cmd_add_arg (cmd3, "none");
+    guestfs_int_cmd_add_arg (cmd3, "-machine");
+    guestfs_int_cmd_add_arg (cmd3,
+#ifdef MACHINE_TYPE
+                             MACHINE_TYPE ","
+#endif
+                             "accel=kvm:tcg");
+    guestfs_int_cmd_add_arg (cmd3, "-L");
+    guestfs_int_cmd_add_arg (cmd3, "?");
+    guestfs_int_cmd_set_stdout_callback (cmd3, read_all,
&data->qemu_datadirs,
+                                         CMD_STDOUT_FLAG_WHOLE_BUFFER);
+    r = guestfs_int_cmd_run (cmd3);
+    if (r == -1 || !WIFEXITED (r) || WEXITSTATUS (r) != 0)
+      goto error;
+  }
+  else
+    data->qemu_datadirs = safe_strdup (g, "");
+
   return 0;
 
  error:
@@ -342,6 +389,32 @@ guestfs_int_qemu_supports_device (guestfs_h *g,
   return strstr (data->qemu_devices, device_name) != NULL;
 }
 
+/**
+ * Test if a named BIOS is supported by qemu.
+ */
+int
+guestfs_int_qemu_supports_bios (guestfs_h *g,
+                                const struct qemu_data *data,
+                                const char *bios_name)
+{
+  CLEANUP_FREE_STRING_LIST char **datadirs;
+  size_t i;
+
+  datadirs = guestfs_int_split_string ('\n', data->qemu_datadirs);
+  if (datadirs == NULL)
+    return 0;          /* ignore errors, return false which is safe */
+
+  for (i = 0; datadirs[i] != NULL; ++i) {
+    CLEANUP_FREE char *path;
+
+    path = safe_asprintf (g, "%s/%s", datadirs[i], bios_name);
+    if (access (path, R_OK) == 0)
+      return 1;
+  }
+
+  return 0;
+}
+
 static int
 old_or_broken_virtio_scsi (guestfs_h *g, const struct qemu_data *data)
 {
-- 
2.7.4

This is a cut-down version of the SeaBIOS configuration optimized for
booting a Linux kernel with the -kernel option on x86.  It was added
in qemu 2.7.  Use it if available.
---
 src/launch-direct.c  | 6 ++++++
 src/launch-libvirt.c | 9 +++++++++
 2 files changed, 15 insertions(+)

diff --git a/src/launch-direct.c b/src/launch-direct.c
index 0eece9c..397672a 100644
--- a/src/launch-direct.c
+++ b/src/launch-direct.c
@@ -449,6 +449,12 @@ launch_direct (guestfs_h *g, void *datav, const char *arg)
   ADD_CMDLINE ("-initrd");
   ADD_CMDLINE (initrd);
 
+  if (guestfs_int_qemu_supports_bios (g, data->qemu_data,
"bios-fast.bin")) {
+    /* Use the fast variant of SeaBIOS. */
+    ADD_CMDLINE ("-bios");
+    ADD_CMDLINE ("bios-fast.bin");
+  }
+
   /* Add a random number generator (backend for virtio-rng).  This
    * isn't strictly necessary but means we won't need to hang around
    * when needing entropy.
diff --git a/src/launch-libvirt.c b/src/launch-libvirt.c
index 67cbde2..1f5e87c 100644
--- a/src/launch-libvirt.c
+++ b/src/launch-libvirt.c
@@ -1162,6 +1162,15 @@ construct_libvirt_xml_boot (guestfs_h *g,
 	} end_element ();
       }
     }
+#if defined(__i386__) || defined(__x86_64__)
+    /* XXX libvirt should provide a way to detect if bios-fast.bin exists */
+    else if (guestfs_int_qemu_version_ge (params->data->qemu_data, 2, 7))
{
+      /* Use the fast variant of SeaBIOS. */
+      start_element ("loader") {
+        string ("bios-fast.bin");
+      } end_element ();
+    }
+#endif
 
     start_element ("kernel") {
       string (params->kernel);
-- 
2.7.4