Re: [PATCH 1/3] libxl: make libxl__need_xenpv_qemu() operate on domain config

[Juergen Gross <jgross@suse.com>]

On 17/03/16 17:53, George Dunlap wrote:
> On Thu, Mar 10, 2016 at 3:00 PM, Juergen Gross <jgross@suse.com> wrote:
>> libxl__need_xenpv_qemu() is called with configuration data for console,
>> vfbs, disks and channels today in order to evaluate the need for
>> starting a device model for a pv domain.
>>
>> The console data is local to the caller and setup in a way to never
>> require a device model. All other data is taken from the domain config
>> structure.
>>
>> In order to support other device backends via qemu change the interface
>> of libxl__need_xenpv_qemu() to take the domain config structure as
>> input instead of the single device arrays.
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
>> ---
>>  tools/libxl/libxl_create.c   |  9 +------
>>  tools/libxl/libxl_dm.c       | 59 ++++++++++++--------------------------------
>>  tools/libxl/libxl_internal.h |  5 +---
>>  3 files changed, 18 insertions(+), 55 deletions(-)
>>
>> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
>> index 61b5c01..0e2b0a0 100644
>> --- a/tools/libxl/libxl_create.c
>> +++ b/tools/libxl/libxl_create.c
>> @@ -1304,7 +1304,6 @@ static void domcreate_launch_dm(libxl__egc *egc, libxl__multidev *multidev,
>>      }
>>      case LIBXL_DOMAIN_TYPE_PV:
>>      {
>> -        int need_qemu = 0;
>>          libxl__device_console console;
>>          libxl__device device;
>>
>> @@ -1314,17 +1313,11 @@ static void domcreate_launch_dm(libxl__egc *egc, libxl__multidev *multidev,
>>          }
>>
>>          init_console_info(gc, &console, 0);
>> -
>> -        need_qemu = libxl__need_xenpv_qemu(gc, 1, &console,
>> -                d_config->num_vfbs, d_config->vfbs,
>> -                d_config->num_disks, &d_config->disks[0],
>> -                d_config->num_channels, &d_config->channels[0]);
>> -
>>          console.backend_domid = state->console_domid;
>>          libxl__device_console_add(gc, domid, &console, state, &device);
>>          libxl__device_console_dispose(&console);
>>
>> -        if (need_qemu) {
>> +        if (libxl__need_xenpv_qemu(gc, d_config)) {
>>              dcs->dmss.dm.guest_domid = domid;
>>              libxl__spawn_local_dm(egc, &dcs->dmss.dm);
>>              return;
>> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
>> index 4aca38e..4b840f4 100644
>> --- a/tools/libxl/libxl_dm.c
>> +++ b/tools/libxl/libxl_dm.c
>> @@ -2107,61 +2107,34 @@ int libxl__destroy_device_model(libxl__gc *gc, uint32_t domid)
>>                  GCSPRINTF("/local/domain/%d/image/device-model-pid", domid));
>>  }
>>
>> -int libxl__need_xenpv_qemu(libxl__gc *gc,
>> -        int nr_consoles, libxl__device_console *consoles,
>> -        int nr_vfbs, libxl_device_vfb *vfbs,
>> -        int nr_disks, libxl_device_disk *disks,
>> -        int nr_channels, libxl_device_channel *channels)
>> +int libxl__need_xenpv_qemu(libxl__gc *gc, libxl_domain_config *d_config)
>>  {
>> -    int i, ret = 0;
>> +    int i, ret;
>>      uint32_t domid;
>>
>> -    /*
>> -     * qemu is required in order to support 2 or more consoles. So switch all
>> -     * backends to qemu if this is the case
>> -     */
>> -    if (nr_consoles > 1) {
>> -        for (i = 0; i < nr_consoles; i++)
>> -            consoles[i].consback = LIBXL__CONSOLE_BACKEND_IOEMU;
>> +    ret = libxl__get_domid(gc, &domid);
>> +    if (ret) goto out;
> 
> Doesn't this mean that if libxl__get_domid() fails,
> libxl__need_xenpv_qemu() will effectively return "true"?
> 
> I realize this is a bug in the existing code but there's no need to be
> bug-for-bug compatible here. :-)
> 
> Maybe add an 'rc' variable, and make this:
> 
> rc = libxl__get_domid();
> if(rc) goto out;

Okay, will do (next week).

> 
> Other than that, looks good to me.

Thanks,

Juergen


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