topic Re: core dump question in Operating System - HP-UX

core dump question

yatin — Thu, 11 Mar 2004 06:55:13 GMT

I am reading coredump using cr_read. how can I read value stored at 0x440c4000.I cannot use adb or q4 or any other debuger as i want to read the value into variable in c program

Re: core dump question

Laurent Menase — Thu, 11 Mar 2004 08:44:13 GMT

you can use adb
echo "0x440c4000/X\n0x440c4000?X"|adb myexecutable thecorefile

the first will be read from the core dump.
the second from the executable

Re: core dump question

Dietmar Konermann — Thu, 11 Mar 2004 10:42:03 GMT

Hmm... cr_read(3) and libcrash(5) are designed for _system_ crash dumps. Are you really talking about system crash dumps... or are you trying to read from a standard user process core file?

Re: core dump question

yatin — Thu, 11 Mar 2004 23:31:23 GMT

I am talking about system crash dumps

Re: core dump question

Laurent Menase — Fri, 12 Mar 2004 03:33:28 GMT

which version of HPUX?

Re: core dump question

yatin — Fri, 12 Mar 2004 04:02:23 GMT

I am using HP 11

Re: core dump question

Laurent Menase — Fri, 12 Mar 2004 04:25:18 GMT

On 11.X usually crashdump don't contain user data pages,
This can be configured with crashconf.

If you have a full dump - usually not-
then with q4:
1) find the process structure in the proctable,
2)look at the pregions in the vas of that process,
3) and look for your address in the vas ( look only at the vaddr ) to find the space.
4) ex thespace.theaddress using L
( L is for long)

you have to do the same with cr_read()
If your program is able to display its spaceid for that address, it is more simple.

Re: core dump question

yatin — Fri, 12 Mar 2004 05:06:12 GMT

hi Laurent
Thanks for your help but can u be more specific i din't understand what u meant can u explain me with some example

Re: core dump question

Don Morris_1 — Fri, 12 Mar 2004 14:31:55 GMT

If 0x440c4000 is the *physical* address of what you want to read, just divide by the system page size (you can get that from sysconf() ).

If you're trying to read the data at kernel virtual address 0x440c4000, then you'll have to translate the virtual address first. That means you'll need to load up the hashed page directory first.... and you'll need to know how to calculate the indices properly, etc.

If you know HP-UX kernel internals well, this should be doable.

If not (and you don't want to take the classes to learn), I'd seriously rethink your approach. You could after all just use the system() call to invoke adb to go find this for you. (And if your heart is set on reading the dump yourself... you could creatively let adb do your translating for you as well).

Re: core dump question

Paddy_1 — Fri, 12 Mar 2004 14:51:37 GMT

Alternatively use a expect script that can automate the fetching of the variables and then plug these values into a C program.

Re: core dump question

yatin — Sat, 13 Mar 2004 02:10:46 GMT

Paddy i dint get u.

Re: core dump question

yatin — Mon, 22 Mar 2004 05:40:36 GMT

How can i use adb to to just translate kernel virtual address to physical address