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Re: [libvirt] [PATCH v2 2/3] qemu: add support for dump-guest-core option



On 20.09.2012 10:58, Martin Kletzander wrote:
> The "dump-guest-core' option is new option for the machine type
> (-machine pc,dump-guest-core) that controls whether the guest memory
> will be marked as dumpable.
> 
> While testing this, I've found out that the value for the '-M' options
> is not parsed correctly when additional parameters are used. However,
> when '-machine' is used for the same options, it gets parsed as
> expected. That's why this patch also modifies the parsing and creating
> of the command line, so both '-M' and '-machine' are recognized. In
> QEMU's help there is only mention of the 'machine parameter now with
> no sign of the older '-M'.
> ---
>  src/qemu/qemu_capabilities.c |  4 +++
>  src/qemu/qemu_capabilities.h |  1 +
>  src/qemu/qemu_command.c      | 81 +++++++++++++++++++++++++++++++++++++++-----
>  tests/qemuhelptest.c         |  3 +-
>  4 files changed, 79 insertions(+), 10 deletions(-)
> 
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 3582cbd..4b52dc5 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -182,6 +182,7 @@ VIR_ENUM_IMPL(qemuCaps, QEMU_CAPS_LAST,
>                "seccomp-sandbox",
> 
>                "reboot-timeout", /* 110 */
> +              "dump-guest-core",
>      );
> 
>  struct _qemuCaps {
> @@ -1243,6 +1244,9 @@ qemuCapsComputeCmdFlags(const char *help,
>      if (strstr(help, "-no-shutdown") && (version < 14000 || version > 15000))
>          qemuCapsSet(caps, QEMU_CAPS_NO_SHUTDOWN);
> 
> +    if (strstr(help, "dump-guest-core=on|off"))
> +        qemuCapsSet(caps, QEMU_CAPS_DUMP_GUEST_CORE);
> +
>      /*
>       * Handling of -incoming arg with varying features
>       *  -incoming tcp    (kvm >= 79, qemu >= 0.10.0)
> diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
> index 2201cb3..a069f42 100644
> --- a/src/qemu/qemu_capabilities.h
> +++ b/src/qemu/qemu_capabilities.h
> @@ -146,6 +146,7 @@ enum qemuCapsFlags {
>      QEMU_CAPS_SCSI_DISK_WWN      = 108, /* Is scsi-disk.wwn available? */
>      QEMU_CAPS_SECCOMP_SANDBOX    = 109, /* -sandbox */
>      QEMU_CAPS_REBOOT_TIMEOUT     = 110, /* -boot reboot-timeout */
> +    QEMU_CAPS_DUMP_GUEST_CORE    = 111, /* dump-guest-core-parameter */
> 
>      QEMU_CAPS_LAST,                   /* this must always be the last item */
>  };
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 3807596..52ad4d2 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -4306,6 +4306,45 @@ no_memory:
>      goto cleanup;
>  }
> 
> +static int
> +qemuBuildMachineArgStr(virCommandPtr cmd,
> +                       const virDomainDefPtr def,
> +                       qemuCapsPtr caps)
> +{
> +    /* This should *never* be NULL, since we always provide
> +     * a machine in the capabilities data for QEMU. So this
> +     * check is just here as a safety in case the unexpected
> +     * happens */
> +    if (!def->os.machine)
> +        return 0;
> +
> +    if (!def->mem.dump_core) {
> +        /* if no parameter to the machine type is needed, we still use
> +         * '-M' to keep the most of the compatibility with older versions.
> +         */
> +        virCommandAddArgList(cmd, "-M", def->os.machine, NULL);

I wonder if we should switch to -machine unconditionally on enough new
qemu (option was introduced in 0.15) and leave -M just for backwards
compatibility since qemu is (sort of) maintaining -M just because of us.
 But that'd be a separate patch anyway.

> +    } else {
> +        if (!qemuCapsGet(caps, QEMU_CAPS_DUMP_GUEST_CORE)) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                           "%s", _("dump-guest-core is not available "
> +                                   " with this QEMU binary"));
> +            return -1;
> +        }
> +
> +        /* However, in case there is a parameter to be added, we need to
> +         * use the "-machine" parameter because qemu is not parsing the
> +         * "-M" correctly */
> +        virCommandAddArg(cmd, "-machine");
> +        virCommandAddArgFormat(cmd,
> +                               "%s,%s=%s",
> +                               def->os.machine,
> +                               "dump-guest-core",
> +                               virDomainMemDumpTypeToString(def->mem.dump_core));

This looks weird to me:
s/%s,%s=%s/%s,dump-guest-core=%s/

> +    }
> +
> +    return 0;
> +}
> +
>  static char *
>  qemuBuildSmpArgStr(const virDomainDefPtr def,
>                     qemuCapsPtr caps)
> @@ -4498,12 +4537,8 @@ qemuBuildCommandLine(virConnectPtr conn,
>      }
>      virCommandAddArg(cmd, "-S"); /* freeze CPU */
> 
> -    /* This should *never* be NULL, since we always provide
> -     * a machine in the capabilities data for QEMU. So this
> -     * check is just here as a safety in case the unexpected
> -     * happens */
> -    if (def->os.machine)
> -        virCommandAddArgList(cmd, "-M", def->os.machine, NULL);
> +    if (qemuBuildMachineArgStr(cmd, def, caps) < 0)
> +        goto error;
> 
>      if (qemuBuildCpuArgStr(driver, def, emulator, caps,
>                             &ut, &cpu, &hasHwVirt, !!migrateFrom) < 0)
> @@ -8320,10 +8355,38 @@ virDomainDefPtr qemuParseCommandLine(virCapsPtr caps,
>              }
>              if (STREQ(def->name, ""))
>                  VIR_FREE(def->name);
> -        } else if (STREQ(arg, "-M")) {
> +        } else if (STREQ(arg, "-M") ||
> +                   STREQ(arg, "-machine")) {
> +            char *params;
>              WANT_VALUE();
> -            if (!(def->os.machine = strdup(val)))
> -                goto no_memory;
> +            params = strchr(val, ',');
> +            if (params == NULL) {
> +                if (!(def->os.machine = strdup(val)))
> +                    goto no_memory;
> +            } else {
> +                if (!(def->os.machine = strndup(val, params - val)))
> +                    goto no_memory;
> +
> +                while(params++) {
> +                    /* prepared for more "-machine" parameters */
> +                    char *tmp = params;
> +                    params = strchr(params, ',');
> +
> +                    if (STRPREFIX(tmp, "dump-guest-core=")) {
> +                        tmp += strlen("dump-guest-core=");
> +                        if (params) {
> +                            tmp = strndup(tmp, params - tmp);
> +                            if (tmp == NULL)
> +                                goto no_memory;
> +                        }
> +                        def->mem.dump_core = virDomainMemDumpTypeFromString(tmp);
> +                        if (def->mem.dump_core < 0)

I guess qemu refuses to start with dump-guest-core=default but no one
knows. s/</<=/

> +                            def->mem.dump_core = VIR_DOMAIN_MEM_DUMP_DEFAULT;
> +                        if (params)
> +                            VIR_FREE(tmp);
> +                    }
> +                }
> +            }
>          } else if (STREQ(arg, "-serial")) {
>              WANT_VALUE();
>              if (STRNEQ(val, "none")) {
> diff --git a/tests/qemuhelptest.c b/tests/qemuhelptest.c
> index a3d9656..079aef8 100644
> --- a/tests/qemuhelptest.c
> +++ b/tests/qemuhelptest.c
> @@ -846,7 +846,8 @@ mymain(void)
>              QEMU_CAPS_VIRTIO_SCSI_PCI,
>              QEMU_CAPS_BLOCKIO,
>              QEMU_CAPS_SCSI_DISK_WWN,
> -            QEMU_CAPS_SECCOMP_SANDBOX);
> +            QEMU_CAPS_SECCOMP_SANDBOX,
> +            QEMU_CAPS_DUMP_GUEST_CORE);
> 
>      return ret == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
>  }
> 

ACK with nits fixed.

Michal


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