I am using Gentoo, and I updated the system using emerge -uDA. I am no
longer able to mount NFS fileshares on my NFS server (running Debian).

mount neptune:/volumes/vol3a/ /volumes/vol3a/
mount: wrong fs type, bad option, bad superblock on
neptune:/volumes/vol3a/,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so

I have no messages relating to NFS in either syslog or dmesg on the
client, with last messages in dmesg as follows:

dmesg|tail
smc-ultra.c: ISAPnP reports SMC EtherEZ (8416) at i/o 0x240, irq 5.
smc-ultra.c:v2.02 2/3/98 Donald Becker (becker@cesdis.gsfc.nasa.gov)
eth%d: SMC EtherEZ at 0x240, 00:e0:29:4c:ce:16,assigned IRQ 5
programmed-I/O mode.
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
Adding 2706912k swap on /dev/hda8. Priority:-1 extents:1
across:2706912k
Real Time Clock Driver v1.12ac

I performed a system trace as follows:

strace -o/tmp/mount.strace mount neptune:/volumes/vol3a/ /volumes/vol3a/

This produces the following output:

execve("/bin/mount", ["mount", "neptune:/volumes/vol3a/",
"/volumes/vol3a/"], [/
* 22 vars */]) = 0
brk(0) = 0x8056000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or
directory)
open("/etc/ld.so.cache", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=12566, ...}) = 0
mmap2(NULL, 12566, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7f6d000
close(3) = 0
open("/lib/libblkid.so.1", O_RDONLY) = 3
read(3,
"\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\3 60!\0\0004\0\0\0"...,
512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=36312, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
0) = 0xb7
f6c000
mmap2(NULL, 39188, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0)
= 0xb7f
62000
mmap2(0xb7f6a000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRIT
E, 3, 0x7) = 0xb7f6a000
close(3) = 0
open("/lib/libuuid.so.1", O_RDONLY) = 3
read(3,
"\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0P\ 20\0\0004\0\0\0"..., 5
12) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=13824, ...}) = 0
mmap2(NULL, 16608, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0)
= 0xb7f5d000
mmap2(0xb7f60000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2) = 0xb7f60000
close(3) = 0
open("/lib/libc.so.6", O_RDONLY) = 3
read(3,
"\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@a \1\0004\0\0\0"...,
512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=1192036, ...}) = 0
mmap2(NULL, 1197520, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3,
0) = 0xb7e38000
mmap2(0xb7f57000, 12288, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x11f) = 0xb7f57000
mmap2(0xb7f5a000, 9680, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb7f5a000
close(3) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
0) = 0xb7e37000
set_thread_area({entry_number:-1 -> 6, base_addr:0xb7e37700,
limit:1048575, seg_32bit:1, contents:0, read_exec_only:0,
limit_in_pages:1, seg_not_present:0, useable:1}) = 0
mprotect(0xb7f57000, 8192, PROT_READ) = 0
mprotect(0xb7f60000, 4096, PROT_READ) = 0
mprotect(0xb7f6a000, 4096, PROT_READ) = 0
mprotect(0x8053000, 4096, PROT_READ) = 0
mprotect(0xb7f8b000, 4096, PROT_READ) = 0
munmap(0xb7f6d000, 12566) = 0
brk(0) = 0x8056000
brk(0x8077000) = 0x8077000
umask(022) = 022
open("/dev/null", O_RDWR|O_LARGEFILE) = 3
close(3) = 0
getuid32() = 0
geteuid32() = 0
lstat64("/etc/mtab", {st_mode=S_IFREG|0644, st_size=292, ...}) = 0
stat64("neptune:/volumes/vol3a/", 0xbfffbd74) = -1 ENOENT (No such file
or directory)
stat64("/sbin/mount.nfs", 0xbfffbb00) = -1 ENOENT (No such file or
directory)
rt_sigprocmask(SIG_BLOCK, ~[TRAP SEGV RTMIN RT_1], NULL, 8) = 0
stat64("/sbin/mount.nfs", 0xbfffbae0) = -1 ENOENT (No such file or
directory)
mount("neptune:/volumes/vol3a/", "/volumes/vol3a/", "nfs"...,
MS_MGC_VAL, NULL) = -1 EINVAL (Invalid argument)
rt_sigprocmask(SIG_UNBLOCK, ~[TRAP SEGV RTMIN RT_1], NULL, 8) = 0
write(2, "mount: wrong fs type, bad option"..., 134) = 134
write(2, "\n", 1) = 1
stat64("neptune:/volumes/vol3a/", 0xbfffbc70) = -1 ENOENT (No such file
or directory)
write(2, " In some cases useful info"..., 85) = 85
write(2, "\n", 1) = 1
exit_group(32)

Does anyone know what may have gone wrong here?

The kernel is a 2.6.24.3 vanilla kernel on the Gentoo client, running on
an IBM compatible computer using a Pentium compatible processor.

The NFS server is running Debian stable with a 2.6.18-6-486 kernel
(also running on conventional IBM compatible hardware, using a conventional
Pentium processor.)

Thanks in advance to anyone who can help.

Mark.

--
Mark Hobley,
393 Quinton Road West,
Quinton, BIRMINGHAM.
B32 1QE.