[libvirt] (how much) support for kqemu domain

[Eric Blake]

[digging through old mail]

On 07/17/2010 10:58 AM, John Lumby wrote:
>>> I am wondering about
>  the extent to which "old" qemu-0.11.1
>>> and kqemu-1.4.0 are 
> supported by virt-manager.
>>>
>>>
>>
>> It looks for presence of /dev/kqemu and a -no-kqemu arg in
>>
>  QEMU's help. I had no idea that arg had been changed to
>> be 
> -enable-kqemu.  Patches welcome to support that new
>> arg. See 
> qemudBuildCommandLine() & qemudComputeCmdFlags()
>> methods in 
> src/qemu/qemu_conf.c
>>
>> Daniel
>>
> Thanks Daniel for the pointer to the source code .    Interesting "interface".
> 
> Here's my patch  -  works for me but tested only on my own qemu-1.11.1

I never saw a reply to this.  Is this a patch that should be revived and
rebased onto the latest git?

> 
> --- src/qemu/qemu_conf.h.orig    2010-04-23 11:52:47.000000000 -0400
> +++ src/qemu/qemu_conf.h    2010-07-15 15:27:44.000000000 -0400
> @@ -88,6 +88,13 @@ enum qemud_cmd_flags {
>      QEMUD_CMD_FLAG_NO_HPET       = (1LL << 33), /* -no-hpet flag is supported */
>      QEMUD_CMD_FLAG_NO_KVM_PIT    = (1LL << 34), /* -no-kvm-pit-reinjection supported */
>      QEMUD_CMD_FLAG_TDF           = (1LL << 35), /* -tdf flag (user-mode pit catchup) */
> +
> +    /* features added in qemu-0.11.x   jel  */
> +    QEMUD_CMD_FLAG_KQEMU_EXPLICIT = (1LL << 36) /* KQEMU is available but must be explicitly requested
> +                                                ** using options  -enable-kqemu -kernel-kqemu
> +                                                ** note we either specify both or neither
> +                                                **      since qemu domain is always system mode (I think?) jel 
> +                                                */
>  };
>  
>  /* Main driver state */
> --- src/qemu/qemu_conf.c.orig    2010-04-30 08:46:09.000000000 -0400
> +++ src/qemu/qemu_conf.c    2010-07-15 21:15:12.000000000 -0400
> @@ -1130,6 +1130,14 @@ static unsigned long long qemudComputeCm
>  
>      if (strstr(help, "-no-kqemu"))
>          flags |= QEMUD_CMD_FLAG_KQEMU;
> +    /*  here we check for qemu version of *exactly* 0.11.x,
> +    **  which requires different options to select kqemu      jel  */
> +    if (     ( version >= 11000 ) && ( version <= 11999 )
> +     &&  (      ( strstr(help, "-enable-kqemu") )
> +                 || ( strstr(help, "-kernel-kqemu") )
> +             )
> +       )
> +      flags |= ( QEMUD_CMD_FLAG_KQEMU | QEMUD_CMD_FLAG_KQEMU_EXPLICIT );
>      if (strstr(help, "-no-kvm"))
>          flags |= QEMUD_CMD_FLAG_KVM;
>      if (strstr(help, "-enable-kvm"))
> @@ -3431,7 +3439,10 @@ int qemudBuildCommandLine(virConnectPtr 
>      char memory[50];
>      char boot[VIR_DOMAIN_BOOT_LAST];
>      struct utsname ut;
> -    int disableKQEMU = 0;
> +    int disableKQEMU = 0;           /*   0 means don't enable or disable
> +                                    **  +1 means do explicitly disable
> +                                    **  -1 means do explicitly enable (double-negative)
> +                                    */
>      int disableKVM = 0;
>      int enableKVM = 0;
>      int qargc = 0, qarga = 0;
> @@ -3484,10 +3495,24 @@ int qemudBuildCommandLine(virConnectPtr 
>      /* Need to explicitly disable KQEMU if
>       * 1. Guest domain is 'qemu'
>       * 2. The qemu binary has the -no-kqemu flag
> +     *
> +     * and need to explicitly enable KQEMU if
> +     * 1. Guest domain is 'kqemu'
> +     * 2. The qemu binary has the -enable-kqemu flag
>       */
> -    if ((qemuCmdFlags & QEMUD_CMD_FLAG_KQEMU) &&
> -        def->virtType == VIR_DOMAIN_VIRT_QEMU)
> -        disableKQEMU = 1;
> +
> +    if (qemuCmdFlags & QEMUD_CMD_FLAG_KQEMU) {
> +      /*  we need to decide whether to explictly enable,
> +      ** explicitly disable, or neither (default) */
> +      if (def->virtType == VIR_DOMAIN_VIRT_QEMU) {
> +            disableKQEMU = 1;
> +      } else
> +      if (    ( def->virtType == VIR_DOMAIN_VIRT_KQEMU )
> +           && ( qemuCmdFlags & QEMUD_CMD_FLAG_KQEMU_EXPLICIT )
> +         ) {
> +            disableKQEMU = -1;    /*  explicitly enable */
> +      }
> +    }
>  
>      /* Need to explicitly disable KVM if
>       * 1. Guest domain is 'qemu'
> @@ -3617,8 +3642,12 @@ int qemudBuildCommandLine(virConnectPtr 
>          VIR_FREE(cpu);
>      }
>  
> -    if (disableKQEMU)
> +    if (disableKQEMU == 1)
>          ADD_ARG_LIT("-no-kqemu");
> +    else if (disableKQEMU == -1) {
> +        ADD_ARG_LIT("-enable-kqemu");
> +        ADD_ARG_LIT("-kernel-kqemu");
> +    }
>      if (disableKVM)
>          ADD_ARG_LIT("-no-kvm");
>      if (enableKVM)
> 
> 

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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