On Mon, Jun 07, 2010 at 10:13:27AM -0500, Anthony Liguori wrote:
> On 06/07/2010 09:42 AM, Daniel P. Berrange wrote:
> >Add a new QMP monitor command 'query-machines' to discover what
> >machines are defined in the QEMU binary. This is an easily
> >parsable replacement for 'qemu -M ?'
> >
> > [
> > {
> > "name": "pc-0.13",
> > "description": "Standard PC",
> > "default": 0
> > },
> > {
> > "name": "pc",
> > "description": "Standard PC",
> > "canonical": "pc-0.13",
> > "default": 1
> > },
> > {
> > "name": "pc-0.12",
> > "description": "Standard PC",
> > "default": 0
> > },
> > ....
> > ]
> >
> >No legacy readline monitor output is provided.
> >
> >In the future it would be desirable for each machine's QDict to
> >also include details of any qdev devices that are included by
> >default in the machine type.
> >
> >Signed-off-by: Daniel P. Berrange<berra...@redhat.com>
> >---
> > hw/boards.h | 1 +
> > monitor.c | 9 +++++++
> > vl.c | 70
> > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 80 insertions(+), 0 deletions(-)
> >
> >diff --git a/hw/boards.h b/hw/boards.h
> >index 6f0f0d7..2f6003d 100644
> >--- a/hw/boards.h
> >+++ b/hw/boards.h
> >@@ -32,6 +32,7 @@ typedef struct QEMUMachine {
> > } QEMUMachine;
> >
> > int qemu_register_machine(QEMUMachine *m);
> >+void do_info_machines(Monitor *mon, QObject **data);
> >
> > extern QEMUMachine *current_machine;
> >
> >diff --git a/monitor.c b/monitor.c
> >index f0406e8..b6aa2b4 100644
> >--- a/monitor.c
> >+++ b/monitor.c
> >@@ -55,6 +55,7 @@
> > #include "json-streamer.h"
> > #include "json-parser.h"
> > #include "osdep.h"
> >+#include "hw/boards.h"
> >
> > //#define DEBUG
> > //#define DEBUG_COMPLETION
> >@@ -2449,6 +2450,14 @@ static const mon_cmd_t info_cmds[] = {
> > .mhandler.info_new = do_info_version,
> > },
> > {
> >+ .name = "machines",
> >+ .args_type = "",
> >+ .params = "",
> >+ .help = "show the machine boards",
> >+ .user_print = monitor_user_noop,
> >+ .mhandler.info_new = do_info_machines,
> >+ },
> >+ {
> > .name = "commands",
> > .args_type = "",
> > .params = "",
> >diff --git a/vl.c b/vl.c
> >index 0b38d62..8043fac 100644
> >--- a/vl.c
> >+++ b/vl.c
> >@@ -1537,6 +1537,76 @@ static QEMUMachine *find_default_machine(void)
> > return NULL;
> > }
> >
> >+
> >+/**
> >+ * do_info_machines(): Show machine boards
> >+ *
> >+ * Returns a QList object listing all machine boards
> >+ * available with this QEMU target. Each element in
> >+ * the list is a QDict object containing the following
> >+ * keys
> >+ *
> >+ * - "name": short name for the machine board
> >+ * - "description": long description of the board
> >+ * - "alias": name of an alias
> >+ *
> >+ * Example:
> >+ *
> >+ * [
> >+ * {
> >+ * "name": "pc-0.13",
> >+ * "description": "Standard PC",
> >+ * "default": 0
> >+ * },
> >+ * {
> >+ * "name": "pc",
> >+ * "description": "Standard PC",
> >+ * "canonical": "pc-0.13",
> >+ * "default": 1
> >+ * },
> >+ * {
> >+ * "name": "pc-0.12",
> >+ * "description": "Standard PC",
> >+ * "default": 0
> >+ * },
> >+ * ....
> >+ * ]
> >+ *
> >+ */
> >
>
> My only suggestion would be to:
>
> { 'default-machine': 'pc',
> 'machines': [{
> 'name': 'pc',
> 'description': 'Standard PC',
> },...]
> }
>
> I'd drop 'canonical' too. Aliasing is an implementation detail and
> should not be exposed via the ABI.
The alias/canonical mapping is something that libvirt needs to know in
order guarentee stable guest ABI for all configs it has.
What happens is that an app using libvirt will request a guest config
with machine type 'pc', and libvirt resolves that to the canonical
type 'pc-0.12', and then launches QEMU with '-M pc-0.12' instead of
the '-M pc'. If libvirt passed '-M pc' and let QEMU do the canonicalization,
the guest ABI would no longer be stable across QEMU upgrades because the
canonicalization changes to point to the newer version.
Regards,
Daniel
--
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