Hi all.this is my first message in mail list, so correct me if I 'm wrong.
I have a raspberry pi with kernel compiled from (sys-kernel/raspberrypi-source 3.6.11_r20130711,running nfsv4 server.To simplify problem, only a simple directory exported.

Senge-Raspi ~ # cat /etc/exports
# /etc/exports: NFS file systems being exported.  See exports(5).
/export *(fsid=0,rw,no_subtree_check,no_root_squash)
Senge-Raspi ~ # ls -l /export/
total 4
-rw-r--r-- 1 root root 4 Nov 18 12:48 test
Senge-Raspi ~ # cat /export/test
foo

And on my laptop, as nfs client.

senge@Senge-Laptop ~ $ cat /etc/fstab
# <fs>                  <mountpoint>    <type>          <opts>          <dump/pass>

# NOTE: If your BOOT partition is ReiserFS, add the notail option to opts.
/dev/sda1               /boot           ext4            noauto,noatime          1 2
/dev/sda3               /               ext4            noatime                 0 1
/dev/sda2               none            swap            sw                      0 0
/dev/sda4               /mnt/windows    ntfs            noauto                  0 0
59.78.22.20:/           /raspi          nfs4            rw,_netdev,auto,rsize=32768,wsize=32768         0 0
senge@Senge-Laptop ~ $ sudo rc-config restart nfsmount
Restarting init script
 * Starting rpcbind ...                                                                                                                [ ok ]
 * Starting NFS statd ...                                                                                                              [ ok ]
 * Setting up RPC pipefs ...                                                                                                           [ ok ]
 * Starting idmapd ...                                                                                                                 [ ok ]
 * Starting NFS sm-notify ...                                                                                                          [ ok ]
 * Mounting NFS filesystems ...

It hangs here. and in kernel message
[19888.585247] RPC: Registered named UNIX socket transport module.
[19888.585251] RPC: Registered udp transport module.
[19888.585252] RPC: Registered tcp transport module.
[19888.585253] RPC: Registered tcp NFSv4.1 backchannel transport module.
[19889.214956] NFS: Registering the id_resolver key type
[19889.214973] Key type id_resolver registered
[19889.214974] Key type id_legacy registered
[20054.134247] NFS: nfs4_discover_server_trunking unhandled error -512. Exiting with error EIO

sometimes mount succeed, and directory can be accessed. but reading files return error:(without 'dmesg' changed)
senge@Senge-Laptop ~ $ sudo rc-config restart nfsmount
Restarting init script
 * Starting NFS sm-notify ...                                                                                                          [ ok ]
 * Mounting NFS filesystems ...                                                                                                        [ ok ]
senge@Senge-Laptop ~ $ cat /raspi/test
cat: /raspi/test: Input/Output error

But I actually have nfs support on server:
Senge-Raspi ~ # zcat /proc/config.gz | grep -i nfs
# CONFIG_NFS_FS is not set
CONFIG_NFSD=y
CONFIG_NFSD_V2_ACL=y
CONFIG_NFSD_V3=y
CONFIG_NFSD_V3_ACL=y
CONFIG_NFSD_V4=y
# CONFIG_NFSD_FAULT_INJECTION is not set
CONFIG_NFS_ACL_SUPPORT=y
CONFIG_NFS_COMMON=y

However, official pre-compiled kernel(sys-kernel/raspberrypi-image 3.6.11-p20130730) worked fine,
Senge-Raspi ~ # zcat /proc/config.gz | grep -i nfs
CONFIG_NFS_FS=y
CONFIG_NFS_V2=y
CONFIG_NFS_V3=y
CONFIG_NFS_V3_ACL=y
CONFIG_NFS_V4=y
# CONFIG_NFS_SWAP is not set
# CONFIG_NFS_V4_1 is not set
CONFIG_ROOT_NFS=y
CONFIG_NFS_FSCACHE=y
# CONFIG_NFS_USE_LEGACY_DNS is not set
CONFIG_NFS_USE_KERNEL_DNS=y
CONFIG_NFSD=m
CONFIG_NFSD_V2_ACL=y
CONFIG_NFSD_V3=y
CONFIG_NFSD_V3_ACL=y
CONFIG_NFSD_V4=y
# CONFIG_NFSD_FAULT_INJECTION is not set
CONFIG_NFS_ACL_SUPPORT=y
CONFIG_NFS_COMMON=y


I have googled a lot, return few result...any idea appreciated.(sorry for poor English)