Re: kgdb on arm for 2.6

George Anzinger wrote:

> Lance Spaulding wrote:
>
> > Amit Kale wrote:
> >
> > > arm processor doesn't contain hardware support for single step. gdb 
> > > is aware of this and uses breakpoints for this purpose. It sends an 
> > > 's' packet, which if failed tells gdb that stub doesn't support 
> > > single stepping. Gdb uses breakpoints after that.
> > >
> > > -Amit
> > >  
> > How do I get gdb to do this?  When I try to single-step I get the 
> > "invalid reply" message then gdb is basically hung.  I'm using gdb 
> > v6.1.  Also for reference, single-stepping works fine on the same 
> > platform using a old (~ 2 years) version of kgdb and a 2.4 kernel.  
> > It's just the new 2.6 version of kgdb that I can't get working right.
>
>
> I suspect that the new code is not "correctly" rejecting the "s".  
> Could you, with the old 2.4 version, do:
> set debug remote 1
> si
>
>
> Then, if you like, you could compare with the new version.  I suspect 
> the reply to the "si" command is different.  It looks like the current 
> reply is <nil> (i.e. there is a packet but it is just $#<CS> which are 
> all overhead characters).

Here's a step using the old kgdb and 2.4:

(gdb) set debug remote 1
(gdb) si
Sending packet: $m1312c,4#f7...Ack
Packet received: 00a81be9
Sending packet: $m7c3ef8,4#9d...Ack
Packet received: e44c0100
Sending packet: $Z0,14ce4,4#77...Ack
Packet received:
Packet Z0 (software-breakpoint) is NOT supported
Sending packet: $m14ce4,4#2e...Ack
Packet received: 040014e3
Sending packet: $X14ce4,0:#4f...Ack
Packet received: OK
binary downloading suppported by target
Sending packet: $X14ce4,4:\001\000\237ï#e2...Ack
Packet received: OK
Sending packet: $Hc0#db...Ack
Packet received: OK
Sending packet: $c#63...Ack
Packet received: OK
Packet received: S05
Sending packet: $g#67...Ack
Packet received: 
13000000044005f00100000000000000030000000c4005f002000000184005f093000040004b8100503f7c00203f7c0013000000003f7c0013000000e44c01000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000093000060
Sending packet: $X14ce4,4:\004\000\024ã#4e...Ack
Packet received: OK
Sending packet: $m14ce4,4#2e...Ack
Packet received: 040014e3
Sending packet: $m14ce4,4#2e...Ack
Packet received: 040014e3
Sending packet: $m14ce4,4#2e...Ack
Packet received: 040014e3
Sending packet: $m14c48,4#01...Ack
Packet received: 0dc0a0e1
Sending packet: $m14c4c,4#2c...Ack
Packet received: f0d92de9
Sending packet: $m14c50,4#fa...Ack
Packet received: b4309fe5
Sending packet: $m14c54,4#fe...Ack
Packet received: 002093e5
Sending packet: $m14c58,4#02...Ack
Packet received: 04b04ce2
Sending packet: $m14c5c,4#2d...Ack
Packet received: 020c12e3
Sending packet: $m14c60,4#fb...Ack
Packet received: a8709f15
kgdb_isr (irq=19, dev_id=0xf0054004, regs=0x1) at hphook.c:208
(gdb)

And here's an attempted step using the new kgdb and 2.6:

0x000451b0 in $d () at kernel/kgdb.c:1795
(gdb) set debug remote 1
(gdb) si
Sending packet: $vCont?#49...Ack
Packet received:
Packet vCont (verbose-resume) is NOT supported
Sending packet: $Hc0#db...Ack
Packet received: OK
Sending packet: $s#73...Ack
Packet received:
warning: Invalid remote reply:

Any help appreciated.

Thanks,
Lance


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