Date: Thu, 19 Aug 2004 21:04:28 +0200 From: Marco Molteni <molter@tin.it> To: hackers@freebsd.org Subject: remote kernel gdb: break, continue: fatal trap 12 Message-ID: <20040819210428.30f7cf1d.molter@tin.it>
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Hi,
I am playing around with remote gdb on a -current cvsupped 2 days ago.
In gdb I set a breakpoint on ums_open (USB mouse driver, as a module),
in the console I execute cat /dev/ums0, the breakpoint triggers, in gdb
I issue a continue and I get a Fatal trap 12: page fault while in kernel mode,
as detailed below.
Any ideas why?
thanks
marco
(gdb) tr0
(gdb) getsyms
[..]
(gdb) b ums_open
Breakpoint 1 at 0xc072eedf: file /home/usr.src/sys/modules/ums/../../dev/usb/ums.c, line 594.
(gdb) c
=================
cat /dev/ums0
=================
[New Thread 100057]
[Switching to Thread 100057]
Breakpoint 1, ums_open (dev=0xc064ef6c, flag=0x1, fmt=0x2000, p=0xc10242c0) at
/home/usr.src/sys/modules/ums/../../dev/usb/ums.c:594
(gdb) c
Program received signal SIGSEGV, Segmentation fault.
cdevsw_rel (csw=0x0) at /home/usr.src/sys/kern/kern_conf.c:124
/home/usr.src/sys/kern/kern_conf.c:124:3280:beg:0xc0489e14
Fatal trap 12: page fault while in kernel mode
fault virtual address = 0x48
fault code = supervisor write, page not present
instruction pointer = 0x8:0xc0489e14
stack pointer = 0x10:0xcbf6e9c0
frame pointer = 0x10:0xcbf6e9c4
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, def32 1, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process = 559 (cat)
--
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