[SLOF] [PATCH] libnet: Correctly re-initialize the "ip_version" variable each time

Thomas Huth thuth at redhat.com
Sat Apr 6 02:58:09 AEDT 2019

I recently noticed that if you start QEMU with two NICs, and only
want to boot from the second NIC, SLOF only tries to get an IP
address via DHCPv6 instead of trying both, DHCPv4 and DHCPv6. For

$ qemu-system-ppc64 -nic hubport,hubid=1 \
    -nic user,model=virtio,tftp=/.../tftp,bootfile=zImage.pseries
Trying to load:  from: /vdevice/l-lan at 71000002 ...
 Initializing NIC
  Reading MAC address from device: 52:54:00:12:34:56
  Requesting information via DHCP:  007

E3001 (net) Could not get IP address
Trying to load:  from: /pci at 800000020000000/ethernet at 0 ...
 Initializing NIC
  Reading MAC address from device: 52:54:00:12:34:57
  Requesting information via DHCPv6: done
  Using IPv6 address: fec0::5254:ff:fe12:3457

The problem is that we never re-initialize the "ip_version" variable
anymore, so once it has been set to 6, it stays at 6 for the second
network boot attempt, too. Thus reset the variable to 4 at the beginning
of the netload() function.

Signed-off-by: Thomas Huth <thuth at redhat.com>
 lib/libnet/netload.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/libnet/netload.c b/lib/libnet/netload.c
index f7ec341..2dc00f0 100644
--- a/lib/libnet/netload.c
+++ b/lib/libnet/netload.c
@@ -38,7 +38,7 @@
 #define MAX_PKT_SIZE         1720
-static int ip_version = 4;
+static int ip_version;
 typedef struct {
 	char filename[100];
@@ -542,6 +542,8 @@ int netload(char *buffer, int len, char *args_fs, int alen)
 	uint8_t own_mac[6];
 	char *pkt_buffer;
+	ip_version = 4;
 	pkt_buffer = SLOF_alloc_mem(MAX_PKT_SIZE);
 	if (!pkt_buffer) {
 		puts("ERROR: Unable to allocate memory");

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