On small systems (e.g. embedded ones) IP addresses are often configured
by bootloaders and get assigned to kernel via parameter "ip=". If set to
"ip=dhcp", even nameserver entries from DHCP daemons are handled. These
entries exported in /proc/net/pnp are commonly linked by /etc/resolv.conf.
To configure nameservers for networks without DHCP, this patch adds option
<dns0-ip> and <dns1-ip> to kernel-parameter 'ip='.
Signed-off-by: Christoph Fritz <chf.fritz@xxxxxxxxxxxxxx>
Tested-by: Jan Weitzel <j.weitzel@xxxxxxxxx>
---
v2: - fix indent
---
Documentation/filesystems/nfs/nfsroot.txt | 7 +++++
net/ipv4/ipconfig.c | 39 ++++++++++++++++++++++++++--
2 files changed, 43 insertions(+), 3 deletions(-)
diff --git a/Documentation/filesystems/nfs/nfsroot.txt b/Documentation/filesystems/nfs/nfsroot.txt
index ffdd9d8..4ed7875 100644
--- a/Documentation/filesystems/nfs/nfsroot.txt
+++ b/Documentation/filesystems/nfs/nfsroot.txt
@@ -158,6 +158,13 @@ ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>
Default: any
+ <dns0-ip> IP address of first nameserver.
+ Value gets exported by /proc/net/pnp which is often linked
+ on embedded systems by /etc/resolv.conf.
+
+ <dns1-ip> IP address of secound nameserver.
+ Same as above.
+
nfsrootdebug
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index 67e8a6b..1c0e7e0 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -743,14 +743,22 @@ static void __init ic_bootp_init_ext(u8 *e)
/*
- * Initialize the DHCP/BOOTP mechanism.
+ * Predefine Nameservers
*/
-static inline void __init ic_bootp_init(void)
+static inline void __init ic_nameservers_predef(void)
{
int i;
for (i = 0; i < CONF_NAMESERVERS_MAX; i++)
ic_nameservers[i] = NONE;
+}
+
+/*
+ * Initialize the DHCP/BOOTP mechanism.
+ */
+static inline void __init ic_bootp_init(void)
+{
+ ic_nameservers_predef();
dev_add_pack(&bootp_packet_type);
}
@@ -1379,6 +1387,7 @@ static int __init ip_auto_config(void)
int retries = CONF_OPEN_RETRIES;
#endif
int err;
+ unsigned int i;
#ifdef CONFIG_PROC_FS
proc_net_fops_create(&init_net, "pnp", S_IRUGO, &pnp_seq_fops);
@@ -1499,7 +1508,15 @@ static int __init ip_auto_config(void)
&ic_servaddr, &root_server_addr, root_server_path);
if (ic_dev_mtu)
pr_cont(", mtu=%d", ic_dev_mtu);
- pr_cont("\n");
+ for (i = 0; i < CONF_NAMESERVERS_MAX; i++)
+ if (ic_nameservers[i] != NONE) {
+ pr_info(" nameserver%u=%pI4",
+ i, &ic_nameservers[i]);
+ break;
+ }
+ for (i++; i < CONF_NAMESERVERS_MAX; i++)
+ if (ic_nameservers[i] != NONE)
+ pr_cont(", nameserver%u=%pI4\n", i, &ic_nameservers[i]);
#endif /* !SILENT */
return 0;
@@ -1570,6 +1587,8 @@ static int __init ip_auto_config_setup(char *addrs)
return 1;
}
+ ic_nameservers_predef();
+
/* Parse string for static IP assignment. */
ip = addrs;
while (ip && *ip) {
@@ -1613,6 +1632,20 @@ static int __init ip_auto_config_setup(char *addrs)
ic_enable = 0;
}
break;
+ case 7:
+ if (CONF_NAMESERVERS_MAX >= 1) {
+ ic_nameservers[0] = in_aton(ip);
+ if (ic_nameservers[0] == ANY)
+ ic_nameservers[0] = NONE;
+ }
+ break;
+ case 8:
+ if (CONF_NAMESERVERS_MAX >= 2) {
+ ic_nameservers[1] = in_aton(ip);
+ if (ic_nameservers[1] == ANY)
+ ic_nameservers[1] = NONE;
+ }
+ break;
}
}
ip = cp;
--
1.7.2.5
--
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