[Qemu-devel] Re: [PATCH] new parameter boot=on|off for "-net nic" and "-device" NIC devices

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Sep 14, 2010 at 05:46:55PM +0200, Bernhard Kohl wrote:
> This patch was motivated by the following use case: In our system
> the VMs usually have 4 NICs, any combination of virtio-net-pci and
> pci-assign NIC devices. The VMs boot via gPXE preferably over the
> pci-assign devices.
> 
> There is no way to make this working with a combination of the
> current options -net -pcidevice -device -optionrom -boot.
> 
> With the parameter boot=off it is possible to avoid loading
> and using gPXE option ROMs either for old style "-net nic" or
> for "-device" NIC devices. So we can select which NIC is used
> for booting.
> 
> A side effect of the boot=off parameter is that unneeded ROMs
> which might waste memory are not longer loaded. E.g. if you have
> 2 virtio-net-pci and 2 pci-assign NICs in sum 4 option ROMs are
> loaded and the virtio ROMs take precedence over the pci-assign
> ROMs. The BIOS uses the first gPXE ROM which it finds and only
> needs one of them even if there are more NICs of the same type.
> 
> Without using the boot=on|off parameter the current behaviour
> does not change.
> 
> Signed-off-by: Thomas Ostler <thomas.ostler@nsn.com>
> Signed-off-by: Bernhard Kohl <bernhard.kohl@nsn.com>

I think this is useful, however:

- We have bit properties which handle parsing on/off
  and other formats automatically. Please don't use string.
- boot is not a great property name for PCI: what
  you actually do is disable option rom.
  So maybe call it 'rom' or something like that?
- given you have added a property, it can now
  be changed with -device. and visible in -device ?
  This also has an advantage of only applying to pci devices
  (-net option would appear to apply to non-pci but have no effect).
  Please do not add more flag parsing in qdemu-options, net and vl.c

To summarize, just add a qdev bit option and check
the bit.

> ---
>  hw/pci.c        |    8 +++++++-
>  hw/pci.h        |    1 +
>  hw/qdev.c       |    6 ++++++
>  hw/qdev.h       |    1 +
>  net.c           |    8 ++++++++
>  net.h           |    1 +
>  qemu-options.hx |    8 ++++++--
>  vl.c            |   27 +++++++++++++++++++++++++++
>  8 files changed, 57 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index a98d6f3..055a2be 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -71,6 +71,7 @@ static struct BusInfo pci_bus_info = {
>          DEFINE_PROP_UINT32("rombar",  PCIDevice, rom_bar, 1),
>          DEFINE_PROP_BIT("multifunction", PCIDevice, cap_present,
>                          QEMU_PCI_CAP_MULTIFUNCTION_BITNR, false),
> +        DEFINE_PROP_STRING("boot", PCIDevice, boot),
>          DEFINE_PROP_END_OF_LIST()
>      }
>  };
> @@ -1513,6 +1514,10 @@ PCIDevice *pci_nic_init(NICInfo *nd, const char *default_model,
>  
>      pci_dev = pci_create(bus, devfn, pci_nic_names[i]);
>      dev = &pci_dev->qdev;
> +    if (nd->name)
> +        dev->id = qemu_strdup(nd->name);
> +    if (nd->no_boot)
> +        dev->no_boot = 1;
>      qdev_set_nic_properties(dev, nd);
>      if (qdev_init(dev) < 0)
>          return NULL;
> @@ -1693,7 +1698,8 @@ static int pci_qdev_init(DeviceState *qdev, DeviceInfo *base)
>      /* rom loading */
>      if (pci_dev->romfile == NULL && info->romfile != NULL)
>          pci_dev->romfile = qemu_strdup(info->romfile);
> -    pci_add_option_rom(pci_dev);
> +    if (!qdev->no_boot)
> +        pci_add_option_rom(pci_dev);
>  
>      if (qdev->hotplugged) {
>          rc = bus->hotplug(bus->hotplug_qdev, pci_dev, 1);
> diff --git a/hw/pci.h b/hw/pci.h
> index 1eab7e7..20aa038 100644
> --- a/hw/pci.h
> +++ b/hw/pci.h
> @@ -172,6 +172,7 @@ struct PCIDevice {
>      char *romfile;
>      ram_addr_t rom_offset;
>      uint32_t rom_bar;
> +    char *boot;
>  };
>  
>  PCIDevice *pci_register_device(PCIBus *bus, const char *name,
> diff --git a/hw/qdev.c b/hw/qdev.c
> index 35858cb..8445bc9 100644
> --- a/hw/qdev.c
> +++ b/hw/qdev.c
> @@ -249,6 +249,10 @@ DeviceState *qdev_device_add(QemuOpts *opts)
>          qdev_free(qdev);
>          return NULL;
>      }
> +    if (qemu_opt_get(opts, "boot")) {
> +        if (!strcmp("off", qemu_strdup(qemu_opt_get(opts, "boot"))))
> +            qdev->no_boot = 1;
> +    }
>      if (qdev_init(qdev) < 0) {
>          qerror_report(QERR_DEVICE_INIT_FAILED, driver);
>          return NULL;
> @@ -421,6 +425,8 @@ void qdev_set_nic_properties(DeviceState *dev, NICInfo *nd)
>          qdev_prop_exists(dev, "vectors")) {
>          qdev_prop_set_uint32(dev, "vectors", nd->nvectors);
>      }
> +    if (nd->no_boot)
> +        qdev_prop_parse(dev, "boot", "off");
>  }
>  
>  static int next_block_unit[IF_COUNT];
> diff --git a/hw/qdev.h b/hw/qdev.h
> index 579328a..e7df371 100644
> --- a/hw/qdev.h
> +++ b/hw/qdev.h
> @@ -45,6 +45,7 @@ struct DeviceState {
>      QLIST_ENTRY(DeviceState) sibling;
>      int instance_id_alias;
>      int alias_required_for_version;
> +    int no_boot;
>  };
>  
>  typedef void (*bus_dev_printfn)(Monitor *mon, DeviceState *dev, int indent);
> diff --git a/net.c b/net.c
> index 3d0fde7..2370aca 100644
> --- a/net.c
> +++ b/net.c
> @@ -792,6 +792,10 @@ static int net_init_nic(QemuOpts *opts,
>      if (qemu_opt_get(opts, "addr")) {
>          nd->devaddr = qemu_strdup(qemu_opt_get(opts, "addr"));
>      }
> +    if (qemu_opt_get(opts, "boot")) {
> +        if (!strcmp("off", qemu_strdup(qemu_opt_get(opts, "boot"))))
> +            nd->no_boot = 1;
> +    }
>  
>      nd->macaddr[0] = 0x52;
>      nd->macaddr[1] = 0x54;
> @@ -877,6 +881,10 @@ static const struct {
>                  .type = QEMU_OPT_STRING,
>                  .help = "PCI device address",
>              }, {
> +                .name = "boot",
> +                .type = QEMU_OPT_STRING,
> +                .help = "gPXE boot (on (default), off)",
> +            }, {
>                  .name = "vectors",
>                  .type = QEMU_OPT_NUMBER,
>                  .help = "number of MSI-x vectors, 0 to disable MSI-X",
> diff --git a/net.h b/net.h
> index 518cf9c..288059b 100644
> --- a/net.h
> +++ b/net.h
> @@ -132,6 +132,7 @@ struct NICInfo {
>      VLANClientState *netdev;
>      int used;
>      int nvectors;
> +    int no_boot;
>  };
>  
>  extern int nb_nics;
> diff --git a/qemu-options.hx b/qemu-options.hx
> index a0b5ae9..6084aa9 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -959,8 +959,10 @@ DEF("smb", HAS_ARG, QEMU_OPTION_smb, "", QEMU_ARCH_ALL)
>  #endif
>  
>  DEF("net", HAS_ARG, QEMU_OPTION_net,
> -    "-net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
> +    "-net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v][,boot=on|off]\n"
>      "                create a new Network Interface Card and connect it to VLAN 'n'\n"
> +    "                use 'boot=on|off' to enable/disable loading of an option rom;\n"
> +    "                loading enabled is the default\n"
>  #ifdef CONFIG_SLIRP
>      "-net user[,vlan=n][,name=str][,net=addr[/mask]][,host=addr][,restrict=y|n]\n"
>      "         [,hostname=host][,dhcpstart=addr][,dns=addr][,tftp=dir][,bootfile=f]\n"
> @@ -1014,13 +1016,15 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
>  #endif
>      "socket],id=str[,option][,option][,...]\n", QEMU_ARCH_ALL)
>  STEXI
> -@item -net nic[,vlan=@var{n}][,macaddr=@var{mac}][,model=@var{type}] [,name=@var{name}][,addr=@var{addr}][,vectors=@var{v}]
> +@item -net nic[,vlan=@var{n}][,macaddr=@var{mac}][,model=@var{type}] [,name=@var{name}][,addr=@var{addr}][,vectors=@var{v}][,boot=on|off]
>  @findex -net
>  Create a new Network Interface Card and connect it to VLAN @var{n} (@var{n}
>  = 0 is the default). The NIC is an e1000 by default on the PC
>  target. Optionally, the MAC address can be changed to @var{mac}, the
>  device address set to @var{addr} (PCI cards only),
>  and a @var{name} can be assigned for use in monitor commands.
> +Optionally, with @option{boot=on|off}, you can enable/disable the loading of an option
> +rom; by default, loading is enabled.
>  Optionally, for PCI cards, you can specify the number @var{v} of MSI-X vectors
>  that the card should have; this option currently only affects virtio cards; set
>  @var{v} = 0 to disable MSI-X. If no @option{-net} option is specified, a single
> diff --git a/vl.c b/vl.c
> index 3f45aa9..2aad6b1 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -2459,6 +2459,33 @@ int main(int argc, char **argv, char **envp)
>                  if (!qemu_opts_parse(qemu_find_opts("device"), optarg, 1)) {
>                      exit(1);
>                  }
> +
> +                /* check whether option "boot" is present in the cmd string */
> +                /* for this a modified string is created that does not */
> +                /* contain the driver */
> +                /* if "boot" is present and set to "on", the relevant */
> +                /* variables are set in a way that net boot is possible and */
> +                /* that a present "romfile" is loaded for the given device */
> +                /* note that "default_net" is set to zero in order to avoid */
> +                /* creation of a default device if option "-net" is not */
> +                /* present in the complete command line */
> +                {
> +                   char  mod_optarg[128];
> +                   char  *mod_optarg_p;
> +
> +                   if ((mod_optarg_p = strchr(optarg, ',')))
> +                       strcpy(mod_optarg, ++mod_optarg_p);
> +                   else
> +                       strcpy(mod_optarg, optarg);
> +
> +                   if (get_param_value(mod_optarg, 128, "boot", mod_optarg) != 0) {
> +                       if (!strcmp("on", mod_optarg)) {
> +                           char buf[8]="n";
> +                           pstrcpy(boot_devices, sizeof(boot_devices), buf);
> +                           default_net = 0;
> +                       }
> +                   }
> +                }
>                  break;
>              case QEMU_OPTION_smp:
>                  smp_parse(optarg);
> -- 
> 1.7.2.2
>