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SubjectRe: kgdb on EM64T
George Anzinger wrote:
> Wilkerson, Bryan P wrote:
>> Thanks you Tom and George for the tips on using kgdb with
>> 2.6.13-rc4-mm1.
>> I almost have it working but kgdb seems to have a few issues. I can get
>> it running from the dev machine using the kgdb and console=kgdb boot
>> options on the test kernel. The kernel waits as it should and when I
>> attach with "target remote /dev/ttyS0" and I can continue the boot but
>> eventually it gets to a point in the boot where it frees unused kernel
>> memory successfully and then a warning, "unable to open an initial
>> console", followed by, "Kernel panic - not syncing: Attempted to kill
>> init!"
>> Removing the console=kgdb boot option and the machine boots all the way
>> to run level 5. I tried to break into kgdb at this point using the
>> $echo -e "\003" > /dev/ttyS0
>> from the dev machine but the test kernel panics at gdb_interrupt+75 when
>> it receives anything on the serial port. Hmmm...
>> I'm wondering if I'm maybe just the first to try this on EM64T (kernel
>> builds in the arch/x86_64 tree).
> Possibly:). Since the serial port seems to work (i.e. the first test
> above), the fault seems to be in handling the int3. Is int3 the right
> instruction for this machine? If not you would make the change in
> kgdb.h. I think that is the only place it is defined.

Well, I checked, it is "int $3". Why then the panic? If you try the
boot with kgdb (i.e. wait) and the do:
(gdb) disass gdb_interrupt
What do you find at +75?

George Anzinger
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