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authorMark McLoughlin <markmc@redhat.com>2009-10-22 17:43:37 +0100
committerAnthony Liguori <aliguori@us.ibm.com>2009-10-27 12:29:00 -0500
commitbaf74c95802347e218721dbaa331997e11fbf903 (patch)
tree3f413f960230cbfec68d46e790aed12fde9c9810 /net.c
parent424a7f9674bb801c62b7855a8132d14ef25a36e1 (diff)
downloadqemu-baf74c95802347e218721dbaa331997e11fbf903.tar.gz
net: add a vnet_hdr=on|off parameter
This allows people to disable the IFF_VNET_HDR flag, e.g. for debugging purposes or if they know they may migrate the guest to a machine without IFF_VNET_HDR support. It also allows making the lack of IFF_VNET_HDR support an error condition, e.g. in the case where a guest is being migrated from a host which does support it. Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'net.c')
-rw-r--r--net.c42
1 files changed, 32 insertions, 10 deletions
diff --git a/net.c b/net.c
index 8d35b91de5..3d94260168 100644
--- a/net.c
+++ b/net.c
@@ -1494,7 +1494,8 @@ static TAPState *net_tap_fd_init(VLANState *vlan,
}
#if defined (CONFIG_BSD) || defined (__FreeBSD_kernel__)
-static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
+static int tap_open(char *ifname, int ifname_size,
+ int *vnet_hdr, int vnet_hdr_required)
{
int fd;
char *dev;
@@ -1636,7 +1637,8 @@ static int tap_alloc(char *dev, size_t dev_size)
return tap_fd;
}
-static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
+static int tap_open(char *ifname, int ifname_size,
+ int *vnet_hdr, int vnet_hdr_required)
{
char dev[10]="";
int fd;
@@ -1649,13 +1651,15 @@ static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
return fd;
}
#elif defined (_AIX)
-static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
+static int tap_open(char *ifname, int ifname_size,
+ int *vnet_hdr, int vnet_hdr_required)
{
fprintf (stderr, "no tap on AIX\n");
return -1;
}
#else
-static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
+static int tap_open(char *ifname, int ifname_size,
+ int *vnet_hdr, int vnet_hdr_required)
{
struct ifreq ifr;
int fd, ret;
@@ -1668,7 +1672,7 @@ static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
- {
+ if (*vnet_hdr) {
unsigned int features;
if (ioctl(fd, TUNGETFEATURES, &features) == 0 &&
@@ -1676,6 +1680,13 @@ static int tap_open(char *ifname, int ifname_size, int *vnet_hdr)
*vnet_hdr = 1;
ifr.ifr_flags |= IFF_VNET_HDR;
}
+
+ if (vnet_hdr_required && !*vnet_hdr) {
+ qemu_error("vnet_hdr=1 requested, but no kernel "
+ "support for IFF_VNET_HDR available");
+ close(fd);
+ return -1;
+ }
}
if (ifname[0] != '\0')
@@ -1740,7 +1751,7 @@ static int launch_script(const char *setup_script, const char *ifname, int fd)
static int net_tap_init(QemuOpts *opts, int *vnet_hdr)
{
- int fd;
+ int fd, vnet_hdr_required;
char ifname[128] = {0,};
const char *setup_script;
@@ -1748,8 +1759,14 @@ static int net_tap_init(QemuOpts *opts, int *vnet_hdr)
pstrcpy(ifname, sizeof(ifname), qemu_opt_get(opts, "ifname"));
}
- *vnet_hdr = 0;
- TFR(fd = tap_open(ifname, sizeof(ifname), vnet_hdr));
+ *vnet_hdr = qemu_opt_get_bool(opts, "vnet_hdr", 1);
+ if (qemu_opt_get(opts, "vnet_hdr")) {
+ vnet_hdr_required = *vnet_hdr;
+ } else {
+ vnet_hdr_required = 0;
+ }
+
+ TFR(fd = tap_open(ifname, sizeof(ifname), vnet_hdr, vnet_hdr_required));
if (fd < 0) {
return -1;
}
@@ -2698,8 +2715,9 @@ static int net_init_tap(QemuOpts *opts,
if (qemu_opt_get(opts, "fd")) {
if (qemu_opt_get(opts, "ifname") ||
qemu_opt_get(opts, "script") ||
- qemu_opt_get(opts, "downscript")) {
- qemu_error("ifname=, script= and downscript= is invalid with fd=\n");
+ qemu_opt_get(opts, "downscript") ||
+ qemu_opt_get(opts, "vnet_hdr")) {
+ qemu_error("ifname=, script=, downscript= and vnet_hdr= is invalid with fd=\n");
return -1;
}
@@ -3055,6 +3073,10 @@ static struct {
.name = "sndbuf",
.type = QEMU_OPT_SIZE,
.help = "send buffer limit"
+ }, {
+ .name = "vnet_hdr",
+ .type = QEMU_OPT_BOOL,
+ .help = "enable the IFF_VNET_HDR flag on the tap interface"
},
{ /* end of list */ }
},