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Re: gdbstub initial code, v11
- From: Oleg Nesterov <oleg at redhat dot com>
- To: "Frank Ch. Eigler" <fche at redhat dot com>
- Cc: archer at sourceware dot org, utrace-devel at redhat dot com
- Date: Thu, 23 Sep 2010 01:14:51 +0200
- Subject: Re: gdbstub initial code, v11
- References: <20100922022226.GA27400@redhat.com> <y0m1v8lbfhu.fsf@fche.csb>
On 09/22, Frank Ch. Eigler wrote:
>
> oleg wrote:
>
> > [...] Honestly, I don't really know how do the "right thing" here.
> > Anyway, most probably this code will be changed. Like ptrace, ugdb
> > uses ->report_syscall_exit() to synthesize a trap. Unlike ptrace,
> > ugdb_report_signal() doesn't send SIGTRAP to itself but reports
> > SIGTRAP using siginfo_t we have. In any case, whatever we do,
> > multiple tracers can confuse each other.
>
> (It seems to me that a pure gdb report, without a synthetic
> self-injected SIGTRAP, should be fine.)
What do you mean?
> > Next: fully implement g/G/p/P, currently I am a bit confused...
> > But what about features? [...]
>
> You could dig out the old "fishing plan". One demonstrated
> improvement was from simulating (software) watchpoints within the
> gdb stub, instead of having gdb fall back to issing countless
> single-steps with memory-fetch inquiries in between.
When I do 'watch', gdb sends '$Z2'. I am a bit confused, iirc it
was decided I shouldn't play with Z packets now. But I won't
argue.
Oleg.