Add the root= parameter for NFS filesystems. We currently hardcode
v3 and tcp which probably needs to become configurable at some point.
Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
Documentation/filesystems/nfs.rst | 13 +++++++++++++
fs/nfs.c | 24 ++++++++++++++++++++++++
2 files changed, 37 insertions(+)
diff --git a/Documentation/filesystems/nfs.rst b/Documentation/filesystems/nfs.rst
index f4eda5d..4469ac1 100644
--- a/Documentation/filesystems/nfs.rst
+++ b/Documentation/filesystems/nfs.rst
@@ -10,3 +10,16 @@ barebox has readonly support for NFSv3 in UDP mode.
Example::
mount -t nfs 192.168.23.4:/home/user/nfsroot /mnt/nfs
+
+The barebox NFS driver adds a ``linux.bootargs`` device parameter to the NFS device.
+This parameter holds a Linux kernel commandline snippet containing a suitable root=
+option for booting from exactly that NFS share.
+
+Example::
+
+ devinfo nfs0
+ ...
+ linux.bootargs: root=/dev/nfs nfsroot=192.168.23.4:/home/sha/nfsroot/generic-v7,v3,tcp
+
+The options default to ``v3,tcp`` but can be adjusted before mounting the NFS share with
+the ``global.linux.rootnfsopts`` variable
diff --git a/fs/nfs.c b/fs/nfs.c
index 2738c78..5bff54a 100644
--- a/fs/nfs.c
+++ b/fs/nfs.c
@@ -35,6 +35,7 @@
#include <kfifo.h>
#include <linux/sizes.h>
#include <byteorder.h>
+#include <globalvar.h>
#include "parseopt.h"
@@ -1306,6 +1307,23 @@ static int nfs_stat(struct device_d *dev, const char *filename, struct stat *s)
}
}
+static char *rootnfsopts;
+
+static void nfs_set_rootarg(struct nfs_priv *npriv, struct fs_device_d *fsdev)
+{
+ char *str;
+ const char *ip;
+
+ ip = ip_to_string(npriv->server);
+ str = asprintf("root=/dev/nfs nfsroot=%s:%s%s%s",
+ ip, npriv->path, rootnfsopts[0] ? "," : "",
+ rootnfsopts);
+
+ fsdev_set_linux_rootarg(fsdev, str);
+
+ free(str);
+}
+
static int nfs_probe(struct device_d *dev)
{
struct fs_device_d *fsdev = dev_to_fs_device(dev);
@@ -1369,6 +1387,8 @@ static int nfs_probe(struct device_d *dev)
goto err2;
}
+ nfs_set_rootarg(npriv, fsdev);
+
free(tmp);
return 0;
@@ -1421,6 +1441,10 @@ static struct fs_driver_d nfs_driver = {
static int nfs_init(void)
{
+ rootnfsopts = xstrdup("v3,tcp");
+
+ globalvar_add_simple_string("linux.rootnfsopts", &rootnfsopts);
+
return register_fs_driver(&nfs_driver);
}
coredevice_initcall(nfs_init);
--
2.1.4
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