x86_64: 32bit emulation problems
From: Bernd Schubert
Date: Mon Feb 28 2005 - 15:58:10 EST
Hi,
I'm just looking into a very strange problem. Some of our systems have
athlon64 CPUs. Due to our diskless nfs environment we currently still prefer
a 32bit userspace environment, but would like to be able to use a 64-bit
chroot environment.
Well, currently there seems to be a stat64() NFS problem when a x86_64 kernel
is booted and stat64() comes from a 32bit libc.
Here's just an example:
hitchcock:/home/bernd/src/tests# ./test_stat64 /mnt/test/yp
stat() works fine.
hitchcock:/home/bernd/src/tests# ./test_stat32 /mnt/test/yp
stat for /mnt/test/yp failed
The test program looks rather simple:
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
int main(int argc, char **argv)
{
char *dir;
struct stat buf;
dir = argv[1];
if (stat (dir, &buf) == -1)
fprintf(stderr, "stat for %s failed \n", dir);
else
fprintf(stderr, "stat() works fine.\n");
return (0);
}
Here are the strace outputs:
=====================
32bit:
------
hitchcock:/home/bernd/src/tests# strace32 ./test_stat32 /mnt/test/yp
execve("./test_stat32", ["./test_stat32", "/mnt/test/yp"], [/* 39 vars */]) =
0
uname({sys="Linux", node="hitchcock", ...}) = 0
brk(0) = 0x80ad000
brk(0x80ce000) = 0x80ce000
stat64("/mnt/test/yp", {st_mode=S_IFDIR|0755, st_size=2704, ...}) = 0
write(2, "stat for /mnt/test/yp failed \n", 30stat for /mnt/test/yp failed
) = 30
exit_group(0) = ?
64bit:
-------
hitchcock:/home/bernd/src/tests# strace ./test_stat64 /mnt/test/yp
execve("./test_stat64", ["./test_stat64", "/mnt/test/yp"], [/* 39 vars */]) =
0
uname({sys="Linux", node="hitchcock", ...}) = 0
brk(0) = 0x572000
brk(0x593000) = 0x593000
stat("/mnt/test/yp", {st_mode=S_IFDIR|0755, st_size=2704, ...}) = 0
write(2, "stat() works fine.\n", 19stat() works fine.
) = 19
_exit(0) = ?
Anyone having an idea whats going on? The ethereal capture also looks pretty
normal. The kernel of this system is 2.6.9, but it also happens on another
system with 2.6.11-rc5.
As usual we are using unfs3 for /etc and /var, but for me that looks like a
client problem. I'm even not sure if this is limited to NFS at all.
Thanks in advance,
Bernd
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