It was altogether too long since I did any lowlevel programming. I must
admit I don't get a whole lot out of gdb.
[EMAIL PROTECTED] /export/virtual/usermode/machine.test $ gdb --args
/usr/bin/uml_moo root_fs.cow newroot
GNU gdb 6.3 Copyright 2004 Free Software Foundation, Inc. GDB is free
software, covered by the GNU General Public License, and you are welcome
to change it and/or distribute copies of it under certain conditions. Type
"show copying" to see the conditions. There is absolutely no warranty for
GDB. Type "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu"...(no debugging symbols
found)
Using host libthread_db library "/lib/libthread_db.so.1".
(gdb) run
Starting program: /usr/bin/uml_moo root_fs.cow newroot
(no debugging symbols found)
(no debugging symbols found)
Program received signal SIGFPE, Arithmetic exception.
0x00000000004018b1 in ?? ()
(gdb) backtrace
#0 0x00000000004018b1 in ?? ()
#1 0x0000000000400d61 in ?? ()
#2 0x00000000004011ac in ?? ()
#3 0x00002aaaaabddd00 in __libc_start_main () from /lib/libc.so.6
#4 0x0000000000400c5a in ?? ()
#5 0x00007fffffffe2a8 in ?? ()
#6 0x000000000000001c in ?? ()
...
#428 0x4f4c4f4300797469 in ?? ()
#429 0x2f003d4d52455452 in ?? ()
#430 0x2f6e69622f727375 in ?? ()
#431 0x006f6f6d5f6c6d75 in ?? ()
#432 0x0000000000000000 in ?? ()
Cannot access memory at address 0x7ffffffff000
(gdb) c
Continuing.
Program terminated with signal SIGFPE, Arithmetic exception.
The program no longer exists.
(gdb)
Well, this certainly doesn't tell me a whole lot. :-)
[EMAIL PROTECTED] /export/virtual/usermode/machine.test $ strace
/usr/bin/uml_moo root_fs.cow newroot
execve("/usr/bin/uml_moo", ["/usr/bin/uml_moo", "root_fs.cow", "newroot"], [/*
61 vars */]) = 0
uname({sys="Linux", node="ligur.student.mh.se", ...}) = 0
brk(0) = 0x503000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x2aaaaaac0000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=110401, ...}) = 0
mmap(NULL, 110401, PROT_READ, MAP_PRIVATE, 3, 0) = 0x2aaaaaac1000
close(3) = 0
open("/lib/libc.so.6", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\200\315"..., 640) = 640
lseek(3, 624, SEEK_SET) = 624
read(3, "\4\0\0\0\20\0\0\0\1\0\0\0GNU\0\0\0\0\0\2\0\0\0\4\0\0\0"..., 32) = 32
fstat(3, {st_mode=S_IFREG|0755, st_size=1253024, ...}) = 0
mmap(NULL, 2250120, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) =
0x2aaaaabc1000
mprotect(0x2aaaaacdd000, 1086856, PROT_NONE) = 0
mmap(0x2aaaaaddc000, 24576, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x11b000) = 0x2aaaaaddc000
mmap(0x2aaaaade2000, 17800, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x2aaaaade2000
close(3) = 0
mprotect(0x2aaaaaddc000, 12288, PROT_READ) = 0
mprotect(0x2aaaaabbf000, 4096, PROT_READ) = 0
munmap(0x2aaaaaac1000, 110401) = 0
open("/dev/urandom", O_RDONLY) = 3
read(3, "\357\371_gn\31;.", 8) = 8
close(3) = 0
open("root_fs.cow", O_RDONLY) = 3
brk(0) = 0x503000
brk(0x524000) = 0x524000
pread(3, "OOOM\0\0\0\3CR\232%\0\0\0\1\0\20\0\0\0\0\2\0\0\0\20\0\0"..., 4136, 0)
= 4136
--- SIGFPE (Floating point exception) @ 0 (0) ---
+++ killed by SIGFPE +++
This didn't tell me a whole lot either. :-)
I hope any of this was more intelligible to someone else than it was to
me. Otherwise, suggest what I should do further to debug.
// Joel
On Mon, 17 Oct 2005, Blaisorblade wrote:
On Sunday 16 October 2005 18:26, Joel Palmius wrote:
[EMAIL PROTECTED] /export/virtual/usermode/machine.master $ ls -lh
totalt 4,3G
-rwxr-xr-x 1 joepal users 671 16 okt 16.09 config.pl*
lrwxrwxrwx 1 joepal users 12 16 okt 16.09 master.uml -> ../lib/linux*
-rw-r--r-- 1 joepal users 4,1G 14 okt 21.02 root_fs
-rw-r--r-- 1 joepal users 4,1G 16 okt 18.16 root_fs.cow
-rw-r--r-- 1 joepal users 513M 16 okt 16.09 swap_fs
[EMAIL PROTECTED] /export/virtual/usermode/machine.master $ uml_moo -d
root_fs.cow Aritmetiskt fel
[EMAIL PROTECTED] /export/virtual/usermode/machine.master $
uml_moo says "arithmetical error". I'm only guessing this is because the
root/cow files are too large..?
The message is a bit vague, it may be "divide for 0", "overflow in result of
division", value more than an "unsigned int" size, or whatever...
If you know a bit of C and gdb, you can probably gdb it (it's a normal and
little userspace program).... I hope I can do this, but as always, I can't
guarantee deadlines.
Or is it a 64-bit host error?
Yup, we *have* to do another round of fixes on uml_utilities. We're seeing too
many bugs on them of this kind.
// Joel
--
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade
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