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Re: GDB and Dragonball EZ.
- To: Stan Shebs <shebs at cygnus dot com>
- Subject: Re: GDB and Dragonball EZ.
- From: Andrew Cagney <ac131313 at cygnus dot com>
- Date: Tue, 23 Nov 1999 09:53:06 +1100
- CC: davidwilliams at ozemail dot com dot au, gdb at sourceware dot cygnus dot com
- Organization: Cygnus Solutions
- References: <199911222159.NAA24545@andros.cygnus.com>
Stan Shebs wrote:
> Another "small" problem is that I don't have a spare RS-232 port to
> communicate to GDB with. I have only one on my system. I have two options,
> as I see it. Firstly I could share the serial port between GDB and my
> application. One problem with this approach is will make debugging the IrDA
> part of my application more difficult. Secondly I could try and implement a
> software UART using the handshaking lines. Currently I think this second
> option may be better as long as a simple half duplex software UART can be
> implemented and provide adequate communications.
>
> The second option sounds harder to me, but mostly because it sounds like
> some ugly driver hacking. The latest GDB sources include a mechanism
> to allow an application and GDB to share a single line when using the
> remote protocol. Look for the function minitelnet() in remote.c.
Please don't encourage people to use that code. Apart from being due
for a rewrite (to use the event-loop) the implementation also has
technical flaws and shouldn't be considered reliable. The code fails to
escape the ``+'' and ``-'' characters which are used by GDB to ACK/NAK
output packets. This can lead to race conditions where GDB incorrectly
ack's/nack's packets. See readtty().
The output path, however, is fine.
sorry,
Andrew
> Anyway what I would like to know is which parts of GDB to look at and what
> existing drivers/stubs etc I should use as templates for modification? Are
> DLDT drivers appropriate? Is GDB stub ("remote target") appropriate?
>
> I would say so. An example m68k stub is in gdb/m68k-stub.c. It's not
> the prettiest code in the world, but note that there's not even a GPL
> on it; the expectation is that you take and modify for your own purposes.
>
> Please point me in the right direction I am currently lost in a sea of
> documentation and source code with no maps!
>
> Note: I am currenty using ECGS 1.1.2 and have downloaded GDB 4.18
> distribution.
>
> GDB has evolved quite a bit since 4.18, and includes hardware
> breakpoint ("Z packet") and the minitelnet features that you probably
> want to use. You can get a copy of the latest sources from
> sourceware.cygnus.com/gdb. Also check out the user's manuals and the
> internals manuals (in gdb/doc), we've been adding to them recently.
>
> Stan