[OE-core] [PATCH v4 1/1] runqemu: support multiple NICs

[Adrian Freihofer]

From: Adrian Freihofer <adrian.freihofer at siemens.com>

Emulating more than one network interface with runqemu is a bit tricky,
but possible. For example, the following leads to an emulated device with
eth0 and eth1:

QB_NETWORK_DEVICE_prepend = " \
    -device virtio-net-device,mac=52:54:00:12:34:03 \
"

or

QB_NETWORK_DEVICE_append = " \
    -device virtio-net-pci,mac=52:54:00:12:34:03 \
"

When booting Qemu with two NICs, the kernel does not know which
interface the specified ip=192.168.7.... command line argument
should be applied. This delays the boot process for a very long
time and a guest wihtout IP configuration.

This add two new configuraton parameters to runqemu:
QB_CMDLINE_IP_SLIRP and QB_CMDLINE_IP_TAP to explicitely specify the ip=
kernel command line arguments for tap and slirp mode.

Note: Simply adding "::eth0" broke some builds on the Yocto autobuilder.

Signed-off-by: Adrian Freihofer <adrian.freihofer at siemens.com>
---
 meta/classes/qemuboot.bbclass | 14 ++++++++++++++
 scripts/runqemu               | 16 ++++++++++++----
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/meta/classes/qemuboot.bbclass b/meta/classes/qemuboot.bbclass
index 15a9e63f2b..54044c38da 100644
--- a/meta/classes/qemuboot.bbclass
+++ b/meta/classes/qemuboot.bbclass
@@ -36,6 +36,9 @@
 #                    Note, runqemu will replace @MAC@ with a predefined mac, you can set
 #                    a custom one, but that may cause conflicts when multiple qemus are
 #                    running on the same host.
+#                    Note: If more than one interface of type -device virtio-net-device gets added,
+#                          QB_NETWORK_DEVICE_prepend might be used, since Qemu enumerates the eth*
+#                          devices in reverse order to -device arguments.
 #
 # QB_TAP_OPT: netowrk option for 'tap' mode, e.g.,
 #             "-netdev tap,id=net0,ifname=@TAP@,script=no,downscript=no"
@@ -43,6 +46,15 @@
 #
 # QB_SLIRP_OPT: network option for SLIRP mode, e.g., -netdev user,id=net0"
 #
+# QB_CMDLINE_IP_SLIRP: If QB_NETWORK_DEVICE adds more than one network interface to qemu, usually the
+#                      ip= kernel comand line argument needs to be changed accordingly. Details are documented
+#                      in the kernel docuemntation https://www.kernel.org/doc/Documentation/filesystems/nfs/nfsroot.txt
+#                      Example to configure only the first interface: "ip=eth0:dhcp"
+# QB_CMDLINE_IP_TAP: This parameter is similar to the QB_CMDLINE_IP_SLIRP parameter. Since the tap interface requires
+#                    static IP configuration @CLIENT@ and @GATEWAY@ place holders are replaced by the IP and the gateway
+#                    address of the qemu guest by runqemu.
+#                    Example: "ip=192.168.7. at CLIENT@::192.168.7. at GATEWAY@:255.255.255.0::eth0"
+#
 # QB_ROOTFS_OPT: used as rootfs, e.g.,
 #               "-drive id=disk0,file=@ROOTFS@,if=none,format=raw -device virtio-blk-device,drive=disk0"
 #              Note, runqemu will replace "@ROOTFS@" with the one which is used, such as core-image-minimal-qemuarm64.ext4.
@@ -63,6 +75,8 @@ QB_DEFAULT_KERNEL ?= "${KERNEL_IMAGETYPE}"
 QB_DEFAULT_FSTYPE ?= "ext4"
 QB_OPT_APPEND ?= "-show-cursor"
 QB_NETWORK_DEVICE ?= "-device virtio-net-pci,netdev=net0,mac=@MAC@"
+QB_CMDLINE_IP_SLIRP ?= "ip=dhcp"
+QB_CMDLINE_IP_TAP ?= "ip=192.168.7. at CLIENT@::192.168.7. at GATEWAY@:255.255.255.0"
 
 # This should be kept align with ROOT_VM
 QB_DRIVE_TYPE ?= "/dev/sd"
diff --git a/scripts/runqemu b/scripts/runqemu
index dd0aa4b28f..6f24093d77 100755
--- a/scripts/runqemu
+++ b/scripts/runqemu
@@ -185,6 +185,8 @@ class BaseConfig(object):
         self.vmtypes = ('hddimg', 'iso')
         self.fsinfo = {}
         self.network_device = "-device e1000,netdev=net0,mac=@MAC@"
+        self.cmdline_ip_slirp = "ip=dhcp"
+        self.cmdline_ip_tap = "ip=192.168.7. at CLIENT@::192.168.7. at GATEWAY@:255.255.255.0"
         # Use different mac section for tap and slirp to avoid
         # conflicts, e.g., when one is running with tap, the other is
         # running with slirp.
@@ -1032,7 +1034,9 @@ class BaseConfig(object):
 
         if self.fstype == 'nfs':
             self.setup_nfs()
-        self.kernel_cmdline_script += ' ip=dhcp'
+        netconf = " " + self.cmdline_ip_slirp
+        logger.info("Network configuration:%s", netconf)
+        self.kernel_cmdline_script += netconf
         # Port mapping
         hostfwd = ",hostfwd=tcp::2222-:22,hostfwd=tcp::2323-:23"
         qb_slirp_opt_default = "-netdev user,id=net0%s,tftp=%s" % (hostfwd, self.get('DEPLOY_DIR_IMAGE'))
@@ -1147,9 +1151,11 @@ class BaseConfig(object):
         client = gateway + 1
         if self.fstype == 'nfs':
             self.setup_nfs()
-        netconf = "192.168.7.%s::192.168.7.%s:255.255.255.0" % (client, gateway)
-        logger.info("Network configuration: %s", netconf)
-        self.kernel_cmdline_script += " ip=%s" % netconf
+        netconf = " " + self.cmdline_ip_tap
+        netconf = netconf.replace('@CLIENT@', str(client))
+        netconf = netconf.replace('@GATEWAY@', str(gateway))
+        logger.info("Network configuration:%s", netconf)
+        self.kernel_cmdline_script += netconf
         mac = "%s%02x" % (self.mac_tap, client)
         qb_tap_opt = self.get('QB_TAP_OPT')
         if qb_tap_opt:
@@ -1171,8 +1177,10 @@ class BaseConfig(object):
         if self.net_bridge:
             self.setup_net_bridge()
         elif self.slirp_enabled:
+            self.cmdline_ip_slirp = self.get('QB_CMDLINE_IP_SLIRP') or self.cmdline_ip_slirp
             self.setup_slirp()
         else:
+            self.cmdline_ip_tap = self.get('QB_CMDLINE_IP_TAP') or self.cmdline_ip_tap
             self.setup_tap()
 
     def setup_rootfs(self):
-- 
2.25.1