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gdb remote protocol breakpoints (Z0 command)
- From: David Taylor <dtaylor at emc dot com>
- To: gdb at sourceware dot org
- Date: Thu, 19 Jun 2014 10:44:34 -0400
- Subject: gdb remote protocol breakpoints (Z0 command)
- Authentication-results: sourceware.org; auth=none
In the manual the Z0 (insert memory breakpoint) command is summarized
thusly:
Z0,addr,kind[;cond_list...][;cmds:persist,cmd_list...]
Now, cond_list 'is comprised of a series of expressions, concatenated
without separators. Each expression has the following form:
X len,expr
len is the length of the bytecode expression and expr is the actual
conditional expression in bytecode form.
That part is fine. Most of the time when I want a conditional
breakpoint, the expression is expressible in bytecode form. (In fact,
while I won't attest that they've always been so expressible, I don't
recall any that weren't so expressible).
But, it then goes on to describe cmd_list in similar terms.
There are many things you might want to do at a breakpoint that lack
bytecode operators. Just for starters,
. there is no bytecode operator for setting memory
. there is no bytecode operator for setting registers
. there is no bytecode operator for calling arbitrary functions
. there is no 'continue' option (as in: ``after performing the
requested commands, continue the current thread'')
There are other capabilities that I would like as well, but without the
four mentioned above, I don't consider it very useful at all.
Has anyone else thought about these issuses and possibly sketched out
extensions to allow such capabilities?
[The 'continue' command would likely be an extension to the Z0 command,
the others would likely be extensions to the bytecode language.]
If we (EMC) were to do something in our gdb and/or remote stub, I would
want it to be compatible with what others are doing / thinking of doing.
Thanks.
David
--
David Taylor
dtaylor at emc dot com