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

[Bernhard Kohl]

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 <address@hidden>
Signed-off-by: Bernhard Kohl <address@hidden>
---
 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
address@hidden -net nic[,address@hidden,address@hidden,address@hidden 
[,address@hidden,address@hidden,address@hidden
address@hidden -net nic[,address@hidden,address@hidden,address@hidden 
[,address@hidden,address@hidden,address@hidden,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