Re: [libvirt] [PATCH] libxl: allow an <emulator> to be selected in the domain config XML

The emulator path supplied can be any valid path on the system. Note that when setting a device_model, libxl needs us to set the device_model_version too. The device_model_version can be either ...QEMU_XEN: meaning "upstream qemu", the default in xen-4.3 onwards ...QEMU_XEN_TRADITIONAL: the old xen-specific fork We detect the device_model_version by examining the qemu filename: if it is "qemu-dm" then it's the old xen-specific fork. If anything else then we assume "upstream qemu" (whose filename may change in future). Note that if you are using a wrapper script to (eg) adjust the arguments of the old qemu during development, you will have to ensure the wrapper script also has the name "qemu-dm", by placing it in a separate directory.

Signed-off-by: David Scott <dave.scott(a)eu.citrix.com&gt; --- src/libxl/libxl_conf.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 44 insertions(+), 0 deletions(-) diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c index 7e0753a..2aa5a62 100644 --- a/src/libxl/libxl_conf.c +++ b/src/libxl/libxl_conf.c @@ -788,6 +788,46 @@ libxlMakeCapabilities(libxl_ctx *ctx) } int +libxlMakeEmulator(virDomainDefPtr def, libxl_domain_config *d_config) +{ + /* No explicit override means use the default */ + if (!def->emulator) { + return 0; + } + + if (!virFileExists(def->emulator)) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("emulator '%s' not found"), + def->emulator); + return -1; + } + + VIR_FREE(d_config->b_info.device_model); + if ((d_config->b_info.device_model = strdup(def->emulator)) == NULL) { + virReportOOMError(); + return -1; + } + + /* N.B. from xen/tools/libxl/libxl_types.idl: + * "If setting device_model you must set device_model_version too." + * + * The xen-4.3 and later default is "upstream qemu" (QEMU_XEN) + * so we make that the default and special-case the old-style + * "traditional qemu" (QEMU_XEN_TRADITIONAL) + */ + + d_config->b_info.device_model_version = + LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN; + + if (STREQ(basename(def->emulator), "qemu-dm")) + d_config->b_info.device_model_version = + LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL; + + return 0; +} + + +int libxlBuildDomainConfig(libxlDriverPrivatePtr driver, virDomainDefPtr def, libxl_domain_config *d_config) { @@ -811,6 +851,10 @@ libxlBuildDomainConfig(libxlDriverPrivatePtr driver, goto error; } + if (libxlMakeEmulator(def, d_config) < 0) { + goto error; + } + d_config->on_reboot = def->onReboot; d_config->on_poweroff = def->onPoweroff; d_config->on_crash = def->onCrash;