Re: gdb symbol problem

[Jie Zhang <jie dot zhang at analog dot com>]

On 12/28/2009 01:09 PM, Hushan Jia wrote:
> On Mon, Dec 28, 2009 at 12:21 PM, Jie Zhang<jie.zhang@analog.com>  wrote:
> > On 12/28/2009 12:14 PM, Hushan Jia wrote:
> > > On Mon, Dec 28, 2009 at 10:38 AM, Jie Zhang<jie.zhang@analog.com>    wrote:
> > > > On 12/27/2009 11:45 AM, Hushan Jia wrote:
> > > > > On Sun, Dec 27, 2009 at 11:36 AM, Paul Pluzhnikov
> > > > > <ppluzhnikov@google.com>      wrote:
> > > > > > On Sat, Dec 26, 2009 at 6:16 PM, Hushan Jia<hushan.jia@gmail.com>
> > > > > >   wrote:
> > > > > >
> > > > > > > I invoke gdb like this:
> > > > > > >
> > > > > > > [hushan@hushan-t linux-2.6.31.3]$ gdb ./vmlinux
> > > > > >
> > > > > > Oh, you are not debugging a regular application. You probably should
> > > > > > have mentioned that in your initial message.
> > > > >
> > > > > Sorry for forget the important information.
> > > > What's the output of "readelf -S vmlinux"?
> > >
> > > Hi, The output is:
> > >
> > > # readelf -S vmlinux
> > > There are 77 section headers, starting at offset 0x3b569cc:
> > >
> > > Section Headers:
> > >    [Nr] Name              Type            Addr     Off    Size   ES Flg Lk
> > > Inf Al
> > >    [ 0]                   NULL            00000000 000000 000000 00      0
> > >    0  0
> > >    [ 1] .text.head        PROGBITS        c1000000 001000 0000a9 00  AX  0
> > >    0  4
> > >    [ 2] .rel.text.head    REL             00000000 3b575d4 000070 08
> > >   75   1  4
> > >    [ 3] .text             PROGBITS        c10000c0 0010c0 291284 00  AX  0
> > >    0 32
> >
> > It seems the machine was not executing code of your vmlinux. The code in
> > your vmlinux starts from 0xc1000000. But when you connected with GDB, the
> > stopped PC was 0xc0467118, which was just ahead of code sections of your
> > vmlinux. Is it possbile the linux kernel running in your qemu was not the
> > one you told GDB?
>
> Hi, I compiled the kernel on the host machine, and then copy kernel
> and modules files to the qemu virtual machine, they are the same
> files.

OK. Then you need to find out what's at the address 0xc0467118. GDB 
cannot show you the symbol and source line which it doesn't know. 
/proc/kallsyms might be helpful if that address is in kernel.

> and the kgdb seems does not work, if I run c in gdb, then I cannot
> interrupt it using CTRL-C, and the breakpoints are never hit.
> The attached file is the kernel config, and kernel is
> linux-2.6.31.3.tar.bz2, downloaded from kernel.org.
I have no idea about kgdb.


Jie