Date: Fri, 02 Jul 2010 10:13:57 +0800 From: David Xu <davidxu@freebsd.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: John Baldwin <john@baldwin.cx>, freebsd-arch@freebsd.org Subject: Re: Access to siginfo for the signal from debugger Message-ID: <4C2D4B65.8080708@freebsd.org> In-Reply-To: <20100701212710.GP13238@deviant.kiev.zoral.com.ua> References: <20100701134217.GM13238@deviant.kiev.zoral.com.ua> <201007011705.26173.john@baldwin.cx> <20100701212710.GP13238@deviant.kiev.zoral.com.ua>
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Kostik Belousov wrote: > On Thu, Jul 01, 2010 at 05:05:26PM -0400, John Baldwin wrote: >> On Thursday 01 July 2010 09:42:17 am Kostik Belousov wrote: >>> Hi, >>> below is the patch that provides the debugger with access to siginfo >>> of the signal that stopped the debuggee. This allows to see a lot more >>> details for the cause of the process stop. E.g. you can see a fault >>> address if process get SIGSEGV or SIGBUS, you can distinguish between >>> breakpoint-generated SIGTRAP and non-breakpoint, whether the signal >>> was send due to external event etc. >>> >>> The change to struct ptrace_lwpinfo is backward-compatible in the sense >>> that programs that were compiled with old definition for the struct will >>> work on new kernels. >> Nice! Does gdb "just work" with these changes or does it need patching as >> well? > It should "just work", and my testing seems to confirm this. gdb uses > PT_LWPINFO to enumerate the thread ids, and I checked it on mt process. > > As I said, the change is ABI backward-compatible, i.e. you do not need > even to recompile the old program for new kernel. > > Sure, gdb cannot show additional available information without > modifications. Yes, you can add new fields to ptrace_lwpinfo without any problem. To print new fields, you should change the function fbsd_thread_signal_cmd in file src/gnu/usr.bin/gdb/libgdb/fbsd-threads.c after change, you just type 'thread signal' command in gdb to show thread's signal info. The command is freebsd specific, others may or may not have it. Regards, David Xu
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