linuxconsole-dev

problems with the serial console

[Andreas S. <an...@sc...>]

i tried to get the kernel messages and the oops i get to the
serial console, and i failed.

two minicoms can talk to each other over my nullmodem cable, but
no messages come through. 

i had fixed a obvious compilation bug (too man arguments to
handle_sysrq in serial.c), but there seems to be more wrong.

i use the patches by  Aivils Stoss and work with a backport on
2.4.19. My ultimat aim is to get a mult-console box for two (or
more) people.

Re: problems with the serial console

[Andreas S. <an...@sc...>]

* Andreas Schuldei (an...@sc...) [020913 13:13]:
> i tried to get the kernel messages and the oops i get to the
> serial console, and i failed.

that was because i has enable the magic sys request /kernel
hacking feature, and that broke in serial.c. Note that Aivils did
not backport ruby serial layer rewrite, so this is understandable
not working as it should. however, when the kernel hacking is
disabled, the serial consol works again and i was able to catch
the oops and decode it.

ksymoops -m /boot/System.map-2.4.19-backstreet-ruby /tmp/oops
ksymoops 2.4.6 on i686 2.4.19-backstreet-ruby.  Options used
     -V (default)
     -k /proc/ksyms (default)
     -l /proc/modules (default)
     -o /lib/modules/2.4.19-backstreet-ruby/ (default)
     -m /boot/System.map-2.4.19-backstreet-ruby (specified)

Warning (compare_maps): ksyms_base symbol ip_ct_attach_R__ver_ip_ct_attach not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol ip_route_me_harder_R__ver_ip_route_me_harder not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol neigh_app_ns_R__ver_neigh_app_ns not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_getsockopt_R__ver_nf_getsockopt not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_hook_slow_R__ver_nf_hook_slow not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_hooks_R__ver_nf_hooks not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_register_hook_R__ver_nf_register_hook not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_register_queue_handler_R__ver_nf_register_queue_handler not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_register_sockopt_R__ver_nf_register_sockopt not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_reinject_R__ver_nf_reinject not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_setsockopt_R__ver_nf_setsockopt not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_unregister_hook_R__ver_nf_unregister_hook not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_unregister_queue_handler_R__ver_nf_unregister_queue_handler not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol nf_unregister_sockopt_R__ver_nf_unregister_sockopt not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol sk_chk_filter_R__ver_sk_chk_filter not found in System.map.  Ignoring ksyms_base entry
Warning (compare_maps): ksyms_base symbol sk_run_filter_R__ver_sk_run_filter not found in System.map.  Ignoring ksyms_base entry
Unable to handle kernel NULL pointer dereference at virtual address 00000000
c0178d8b
*pde = 00000000
Oops: 0000
CPU:    0
EIP:    0010:[<c0178d8b>]    Not tainted
Using defaults from ksymoops -t elf32-i386 -a i386
EFLAGS: 00010282
eax: 0000002c   ebx: 00000001   ecx: ee98e440   edx: 00000000
esi: ee986fdc   edi: 00000000   ebp: 00000001   esp: c026fdb4
ds: 0018   es: 0018   ss: 0018
Process swapper (pid: 0, stackpage=c026f000)
Stack: 00000001 ee986fdc ee986fdc 0000002c 0000000a c0178fb5 00000000 0000002c
       00000001 c01b01be ee98e440 00000001 0000002c 00000001 00000001 ee98421c
       ee986fdc ee984000 c186e1a0 c186e1a0 ee98e440 f08be4ae ee986fdc 00000001
Call Trace:    [<c0178fb5>] [<c01b01be>] [<f08be4ae>] [<f08bbf66>] [<f08bc221>]
  [<f08bc2d7>] [<f08bc312>] [<f08cc204>] [<f08cc579>] [<f08cc7c2>] [<c0110001>]
  [<c010985d>] [<c01099c6>] [<c0106bd0>] [<c0106bd0>] [<c0106bd0>] [<c0106bd0>]
  [<c0106bf3>] [<c0106c59>] [<c0105000>] [<c0105027>]
Code: 8b 37 83 fd 02 74 16 8a 44 24 1c 00 c0 89 ea 30 d0 0f b6 c0


>>EIP; c0178d8b <kbd_keycode+f/21c>   <=====

>>ecx; ee98e440 <_end+2e6d1b28/305ef748>
>>esi; ee986fdc <_end+2e6ca6c4/305ef748>
>>esp; c026fdb4 <init_task_union+1db4/2000>

Trace; c0178fb5 <kbd_event+1d/3c>
Trace; c01b01be <input_event+2ee/308>
Trace; f08be4ae <[hid]hidinput_hid_event+16a/190>
Trace; f08bbf66 <[hid]hid_process_event+22/30>
Trace; f08bc221 <[hid]hid_input_field+2ad/2ec>
Trace; f08bc2d7 <[hid]hid_input_report+77/a0>
Trace; f08bc312 <[hid]hid_irq_in+12/18>
Trace; f08cc204 <[usb-uhci]process_interrupt+a8/228>
Trace; f08cc579 <[usb-uhci]process_urb+7d/200>
Trace; f08cc7c2 <[usb-uhci]uhci_interrupt+c6/12c>
Trace; c0110001 <apm_bios_call_simple+29/6c>
Trace; c010985d <handle_IRQ_event+31/5c>
Trace; c01099c6 <do_IRQ+6a/a8>
Trace; c0106bd0 <default_idle+0/28>
Trace; c0106bd0 <default_idle+0/28>
Trace; c0106bd0 <default_idle+0/28>
Trace; c0106bd0 <default_idle+0/28>
Trace; c0106bf3 <default_idle+23/28>
Trace; c0106c59 <cpu_idle+41/54>
Trace; c0105000 <_stext+0/0>
Trace; c0105027 <rest_init+27/28>

Code;  c0178d8b <kbd_keycode+f/21c>
00000000 <_EIP>:
Code;  c0178d8b <kbd_keycode+f/21c>   <=====
   0:   8b 37                     mov    (%edi),%esi   <=====
Code;  c0178d8d <kbd_keycode+11/21c>
   2:   83 fd 02                  cmp    $0x2,%ebp
Code;  c0178d90 <kbd_keycode+14/21c>
   5:   74 16                     je     1d <_EIP+0x1d> c0178da8 <kbd_keycode+2c/21c>
Code;  c0178d92 <kbd_keycode+16/21c>
   7:   8a 44 24 1c               mov    0x1c(%esp,1),%al
Code;  c0178d96 <kbd_keycode+1a/21c>
   b:   00 c0                     add    %al,%al
Code;  c0178d98 <kbd_keycode+1c/21c>
   d:   89 ea                     mov    %ebp,%edx
Code;  c0178d9a <kbd_keycode+1e/21c>
   f:   30 d0                     xor    %dl,%al
Code;  c0178d9c <kbd_keycode+20/21c>
  11:   0f b6 c0                  movzbl %al,%eax

 <0>Kernel panic: Aiee, killing interrupt handler!

16 warnings issued.  Results may not be reliable.

Any comments?

Re: problems with the serial console

[Andreas S. <an...@sc...>]

* Andreas Schuldei (an...@sc...) [020914 01:26]:
> * Andreas Schuldei (an...@sc...) [020913 13:13]:
> Code;  c0178d8b <kbd_keycode+f/21c>   <=====
>    0:   8b 37                     mov    (%edi),%esi   <=====
> Code;  c0178d8d <kbd_keycode+11/21c>
>    2:   83 fd 02                  cmp    $0x2,%ebp
> Code;  c0178d90 <kbd_keycode+14/21c>

this oops takes place in the function kbd_keycode, because vt is
a nullpointer. i added a check for vt==0 and print out some
warning and returnd, and now it crashes no longer.

so why would the vt pointer be NULL?

Re: problems with the serial console

[Brad H. <bh...@bi...>]

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On Sat, 14 Sep 2002 10:36, Andreas Schuldei wrote:
> * Andreas Schuldei (an...@sc...) [020914 01:26]:
> > * Andreas Schuldei (an...@sc...) [020913 13:13]:
> > Code;  c0178d8b <kbd_keycode+f/21c>   <=====
> >    0:   8b 37                     mov    (%edi),%esi   <=====
> > Code;  c0178d8d <kbd_keycode+11/21c>
> >    2:   83 fd 02                  cmp    $0x2,%ebp
> > Code;  c0178d90 <kbd_keycode+14/21c>
>
> this oops takes place in the function kbd_keycode, because vt is
> a nullpointer. i added a check for vt==0 and print out some
> warning and returnd, and now it crashes no longer.
Does this happen with "vanilla" versions of 2.4.19 (or 2.4.20-pre7) or 2.5.34?

Brad



- -- 
http://conf.linux.org.au. 22-25Jan2003. Perth, Australia. Birds in Black.
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Solution: Keyboard initialisation (was: Re: problems with the serial console)

[Andreas S. <an...@sc...>]

* Brad Hards (bh...@bi...) [020914 03:06]:
> On Sat, 14 Sep 2002 10:36, Andreas Schuldei wrote:
> > * Andreas Schuldei (an...@sc...) [020914 01:26]:
> > > * Andreas Schuldei (an...@sc...) [020913 13:13]:
> > > Code;  c0178d8b <kbd_keycode+f/21c>   <=====
> > >    0:   8b 37                     mov    (%edi),%esi   <=====
> > > Code;  c0178d8d <kbd_keycode+11/21c>
> > >    2:   83 fd 02                  cmp    $0x2,%ebp
> > > Code;  c0178d90 <kbd_keycode+14/21c>
> >
> > this oops takes place in the function kbd_keycode, because vt is
> > a nullpointer. i added a check for vt==0 and print out some
> > warning and returnd, and now it crashes no longer.
> Does this happen with "vanilla" versions of 2.4.19 (or 2.4.20-pre7) or 2.5.34?

it can not, since all those can not have multiple independent vt.


However i did dig some more and this problem occures if the
void pointer private is not initialized in kbd_connect. Then it
points to NULL, and booom. The pointer gets dereferenced in
kbd_keycode, where it is supposed to point to the vt_struct of
the controlling terminal. 

This (void pointer private not beeing initialized) 
happens, it there are more keyboards then VTs. The common case in
the bottom of the function does not catch this, it does not touch
private. 

Would it make sense to let private point to some fix point, in
that case? as a (really bad) solution i pointed it at admin_vt,
which results in funny effekts, when one types on the keyboard
and there is no controlling vt. then the characters showed up in
my root ssh session, and i could even close that session. (c:

Anyone who is better at this: what would be a sensible vt to
point to?