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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Re-reading domain configs on domain restart
On Thu, 2012-02-23 at 11:17 +0000, Ian Campbell wrote:
> As another (hopefully simple) idea how about a "xl dom-set-config" or
> similar which (only) updates the config stashed in the userinfo to be
> used on reboot? I would specifically exclude the possibility of this
> reconfiguring the running domain for simplicity.
I've only lightly tested the following, but it seemed to do what I
expected (I used it to change memory from 512 to 1024 for a Windows VM
on reboot).
I think there might be a better name, that better reflects the fact that
it doesn't actually change the config right now, any ideas?
"domain-config-override"?
Thoughts on the general concept?
Ian.
8<-------------------------------------------------------
xl: provide a command to set the saved configuration for a running domain
Pickup this new configuration on reboot.
Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
diff -r 8b82b7435b7d -r 063d98ba8309 docs/man/xl.pod.1
--- a/docs/man/xl.pod.1 Thu Feb 23 12:31:18 2012 +0000
+++ b/docs/man/xl.pod.1 Thu Feb 23 15:14:29 2012 +0000
@@ -148,6 +148,31 @@ soon as it is run.
=back
+=item B<config-update> B<domid> [I<configfile>] [I<OPTIONS>]
+
+Update the saved configuration for a running domain. This has no
+immediate effect but will be applied when the guest is next
+restarted. This command is useful to ensure that runtime modifications
+made to the guest will be preserved when the guest is restarted.
+
+I<configfile> has to be an absolute path to a file.
+
+B<OPTIONS>
+
+=over 4
+
+=item B<-f=FILE>, B<--defconfig=FILE>
+
+Use the given configuration file.
+
+=item B<key=value>
+
+It is possible to pass I<key=value> pairs on the command line to provide
+options as if they were written in the configuration file; these override
+whatever is in the I<configfile>.
+
+=back
+
=item B<console> [I<OPTIONS>] I<domain-id>
Attach to domain I<domain-id>'s console. If you've set up your domains to
diff -r 8b82b7435b7d -r 063d98ba8309 tools/libxl/xl.h
--- a/tools/libxl/xl.h Thu Feb 23 12:31:18 2012 +0000
+++ b/tools/libxl/xl.h Thu Feb 23 15:14:29 2012 +0000
@@ -50,6 +50,7 @@ int main_reboot(int argc, char **argv);
int main_list(int argc, char **argv);
int main_list_vm(int argc, char **argv);
int main_create(int argc, char **argv);
+int main_config_update(int argc, char **argv);
int main_button_press(int argc, char **argv);
int main_vcpupin(int argc, char **argv);
int main_vcpuset(int argc, char **argv);
diff -r 8b82b7435b7d -r 063d98ba8309 tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c Thu Feb 23 12:31:18 2012 +0000
+++ b/tools/libxl/xl_cmdimpl.c Thu Feb 23 15:14:29 2012 +0000
@@ -1201,11 +1201,31 @@ skip_vfb:
xlu_cfg_destroy(config);
}
+static void reload_domain_config(libxl_ctx *ctx, uint32_t domid,
+ uint8_t **config_data, int *config_len)
+{
+ uint8_t *t_data;
+ int ret, t_len;
+
+ ret = libxl_userdata_retrieve(ctx, domid, "xl", &t_data, &t_len);
+ if (ret) {
+ LOG("failed to retrieve guest configuration (rc=%d). "
+ "reusing old configuration", ret);
+ return;
+ }
+
+ free(*config_data);
+ *config_data = t_data;
+ *config_len = t_len;
+}
+
/* Returns 1 if domain should be restarted,
* 2 if domain should be renamed then restarted, or 0 */
static int handle_domain_death(libxl_ctx *ctx, uint32_t domid,
libxl_event *event,
+ uint8_t **config_data, int *config_len,
libxl_domain_config *d_config)
+
{
int restart = 0;
libxl_action_on_shutdown action;
@@ -1260,10 +1280,13 @@ static int handle_domain_death(libxl_ctx
break;
case LIBXL_ACTION_ON_SHUTDOWN_RESTART_RENAME:
+ reload_domain_config(ctx, domid, config_data, config_len);
restart = 2;
break;
case LIBXL_ACTION_ON_SHUTDOWN_RESTART:
+ reload_domain_config(ctx, domid, config_data, config_len);
+
restart = 1;
/* fall-through */
case LIBXL_ACTION_ON_SHUTDOWN_DESTROY:
@@ -1748,7 +1771,9 @@ start:
LOG("Domain %d has shut down, reason code %d 0x%x", domid,
event->u.domain_shutdown.shutdown_reason,
event->u.domain_shutdown.shutdown_reason);
- switch (handle_domain_death(ctx, domid, event, &d_config)) {
+ switch (handle_domain_death(ctx, domid, event,
+ (uint8_t **)&config_data, &config_len,
+ &d_config)) {
case 2:
if (!preserve_domain(ctx, domid, event, &d_config)) {
/* If we fail then exit leaving the old domain in place. */
@@ -1785,6 +1810,12 @@ start:
d_config.c_info.name = strdup(common_domname);
}
+ /* Reparse the configuration in case it has changed */
+ libxl_domain_config_dispose(&d_config);
+ memset(&d_config, 0, sizeof(d_config));
+ parse_config_data(config_file, config_data, config_len,
+ &d_config);
+
/*
* XXX FIXME: If this sleep is not there then domain
* re-creation fails sometimes.
@@ -3394,6 +3425,120 @@ int main_create(int argc, char **argv)
return 0;
}
+int main_config_update(int argc, char **argv)
+{
+ const char *filename = NULL;
+ char *p;
+ char extra_config[1024];
+ void *config_data = 0;
+ int config_len = 0;
+ libxl_domain_config d_config;
+ int opt, rc;
+ int option_index = 0;
+ int debug = 0;
+ static struct option long_options[] = {
+ {"help", 0, 0, 'h'},
+ {"defconfig", 1, 0, 'f'},
+ {0, 0, 0, 0}
+ };
+
+ if (argc < 2) {
+ fprintf(stderr, "xl config-update requires a domain argument\n");
+ help("config-update");
+ exit(1);
+ }
+
+ find_domain(argv[1]);
+ argc--; argv++;
+
+ if (argv[1] && argv[1][0] != '-' && !strchr(argv[1], '=')) {
+ filename = argv[1];
+ argc--; argv++;
+ }
+
+ while (1) {
+ opt = getopt_long(argc, argv, "dhqf:", long_options, &option_index);
+ if (opt == -1)
+ break;
+
+ switch (opt) {
+ case 'd':
+ debug = 1;
+ break;
+ case 'f':
+ filename = optarg;
+ break;
+ case 'h':
+ help("create");
+ return 0;
+ default:
+ fprintf(stderr, "option `%c' not supported.\n", optopt);
+ break;
+ }
+ }
+
+ extra_config[0] = '\0';
+ for (p = extra_config; optind < argc; optind++) {
+ if (strchr(argv[optind], '=') != NULL) {
+ p += snprintf(p, sizeof(extra_config) - (p - extra_config),
+ "%s\n", argv[optind]);
+ } else if (!filename) {
+ filename = argv[optind];
+ } else {
+ help("create");
+ return 2;
+ }
+ }
+ if (filename) {
+ free(config_data); config_data = 0;
+ rc = libxl_read_file_contents(ctx, filename,
+ &config_data, &config_len);
+ if (rc) { fprintf(stderr, "Failed to read config file: %s: %s\n",
+ filename, strerror(errno)); return ERROR_FAIL; }
+ if (strlen(extra_config)) {
+ if (config_len > INT_MAX - (strlen(extra_config) + 2 + 1)) {
+ fprintf(stderr, "Failed to attach extra configration\n");
+ exit(1);
+ }
+ /* allocate space for the extra config plus two EOLs plus \0 */
+ config_data = realloc(config_data, config_len
+ + strlen(extra_config) + 2 + 1);
+ if (!config_data) {
+ fprintf(stderr, "Failed to realloc config_data\n");
+ exit(1);
+ }
+ config_len += sprintf(config_data + config_len, "\n%s\n",
+ extra_config);
+ }
+ } else {
+ fprintf(stderr, "Config file not specified\n");
+ exit(1);
+ }
+
+ memset(&d_config, 0x00, sizeof(d_config));
+
+ parse_config_data(filename, config_data, config_len, &d_config);
+
+ if (debug || dryrun_only)
+ printf_info(default_output_format, -1, &d_config);
+
+ if (!dryrun_only) {
+ fprintf(stderr, "setting dom%d configuration\n", domid);
+ rc = libxl_userdata_store(ctx, domid, "xl",
+ config_data, config_len);
+ if (rc) {
+ fprintf(stderr, "failed to update configuration\n");
+ exit(1);
+ }
+ }
+
+ libxl_domain_config_dispose(&d_config);
+
+ free(config_data);
+
+ return 0;
+}
+
static void button_press(const char *p, const char *b)
{
libxl_trigger trigger;
@@ -3917,7 +4062,6 @@ static int sched_credit_domain_set(
{
int rc;
-
rc = libxl_sched_credit_domain_set(ctx, domid, scinfo);
if (rc)
fprintf(stderr, "libxl_sched_credit_domain_set failed.\n");
diff -r 8b82b7435b7d -r 063d98ba8309 tools/libxl/xl_cmdtable.c
--- a/tools/libxl/xl_cmdtable.c Thu Feb 23 12:31:18 2012 +0000
+++ b/tools/libxl/xl_cmdtable.c Thu Feb 23 15:14:29 2012 +0000
@@ -32,6 +32,15 @@ struct cmd_spec cmd_table[] = {
"-d Enable debug messages.\n"
"-e Do not wait in the background for the death of
the domain."
},
+ { "config-update",
+ &main_config_update, 1,
+ "Update a running domain's saved configuration, used when rebuilding "
+ "the domain after reboot",
+ "<Domain> <ConfigFile> [options] [vars]",
+ "-h Print this help.\n"
+ "-f FILE, --defconfig=FILE\n Use the given
configuration file.\n"
+ "-d Enable debug messages.\n"
+ },
{ "list",
&main_list, 0,
"List information about all/some domains",
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