From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23178 invoked by alias); 21 Aug 2006 18:57:59 -0000 Received: (qmail 23047 invoked by uid 22791); 21 Aug 2006 18:57:56 -0000 X-Spam-Check-By: sourceware.org Received: from ug-out-1314.google.com (HELO ug-out-1314.google.com) (66.249.92.172) by sourceware.org (qpsmtpd/0.31) with ESMTP; Mon, 21 Aug 2006 18:57:51 +0000 Received: by ug-out-1314.google.com with SMTP id u2so1849979uge for ; Mon, 21 Aug 2006 11:57:48 -0700 (PDT) Received: by 10.66.244.10 with SMTP id r10mr3868969ugh; Mon, 21 Aug 2006 11:57:48 -0700 (PDT) Received: by 10.67.101.17 with HTTP; Mon, 21 Aug 2006 11:57:48 -0700 (PDT) Message-ID: Date: Mon, 21 Aug 2006 18:57:00 -0000 From: "Cai Qian" To: Neo Subject: Re: Virtual Machine and GDB Cc: gdb@sourceware.org In-Reply-To: <44E9FBC3.4000201@cse.unl.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20060821000736.GA2596@nevyn.them.org> <44E9E787.9010202@cse.unl.edu> <44E9FBC3.4000201@cse.unl.edu> Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2006-08/txt/msg00172.txt.bz2 Hi, On 8/21/06, Neo wrote: > Cai, > > Please see my comments following. > > Neo > > Cai Qian wrote: > > Hi, > > > > On 8/21/06, Neo wrote: > >> Cai, > >> > >> I am wondering why you need to debug the VM remotely. Maybe you have > >> your own requirements, such as for embedded systems. But I think you > >> need to first make sure you can debug any binary running on your target > >> board remotely. Then, you can treat the VM as the rest ordinary binary. > >> > > > > I don't want to debug VM itself here, but executable running on the > > VM. As my VM has a new instruction set, and GDB is quite unlikely to > > run locally. > > > I think the gdb will not help for this case. What you need is a debugger > provided by the VM. For JVM, you need to use the jdb to debug your > "executable" code on the top of VM. And what do > you mean "new instruction set"? Are they new instructions for the VM or > the target arch? OK. The VM does not have a debugger at the moment. That is why I try to debug remotely. "New instruction set" means it is not i386, SPARC, SuperH etc, and GDB does not support the arch yet. > >> For JVM 1.4.2 and 1.5, I have successfully debugged it with the latest > >> gdb locally. > >> > > > > Sounds interesting. Any information about how you achieve that? > > > I think this would be quite straight forward just like debugging other > binaries running on Linux host, since the latest gdb includes the > patches to handle execve. > >> Thanks, > >> Neo > >> > >> Cai Qian wrote: > >> > Hi, > >> > > >> > On 8/21/06, teawater wrote: > >> >> Does GDB support the ARCH of you VM? > >> >> > >> > > >> > Sorry, what do you mean by GDB support the ARCH of VM? Do you mean > >> > port GDB? Does it really necessary to port GDB to the VM? At the > >> > moment, GDB can't run natively on my VM, nor gdbserver. I am wondering > >> > if I can still do remote debugging. According to the document [1], it > >> > seems I can create a remote stub for the target, and then link it to > >> > the program I am going to run on the target, ie, to implement at least > >> > the following functions, > >> > > >> > getDebugChar, putDebugChar, flush_i_cache, memset, exceptionHandler > >> > > >> > Although there are lots of things unclear, > >> > > >> > 1) The doc said "int getDebugChar() > >> > Write this subroutine to read a single character from the serial > >> > port. It may be identical to getchar for your target system; a > >> > different name is used to allow you to distinguish the two if you > >> > wish". However, the serial port is not possible for me, so I assume > >> > here it should be "read a single character from the socket", and I > >> > also work for stub. At the moment, I am not sure how to write this > >> > function, because there is no read syscall in VM. Not sure if it will > >> > be better to port Glibc or newlib first. > >> > > >> > 2) Can't find information on what kind of debug features I can have > >> > when after implementing the remote stub. Breakpoint, watchpoint, > >> > single step? > >> > > >> > 3) Not sure how to write a download program to download executable > >> > from target to host in a debug session. > >> > > >> > [1] > >> http://sources.redhat.com/gdb/current/onlinedocs/gdb_18.html#SEC160 > >> > > >> > Qian > >> > > >> >> On 8/21/06, Cai Qian wrote: > >> >> > Hi, > >> >> > > >> >> > On 8/21/06, teawater wrote: > >> >> > > I think you need add a GDBRSP server function to your VM. GDBRSP > >> >> > > support TCP/IP. Read > >> >> > > http://sources.redhat.com/gdb/onlinedocs/gdb_33.html. > >> >> > > But I think you need make GDB support your ARCH first. Maybe > >> my doc > >> >> > > "Porting GDB(1)" (http://teawater.googlepages.com/epgdb1.pdf) is > >> >> > > helpful. > >> >> > > > >> >> > > >> >> > There probably no need to port the whole GDB to my VM (which it is > >> >> > quite difficult at the moment). I just want to have an ability > >> to do > >> >> > remote debugging. If GDB RSP can support TCP/IP, a remote stub and > >> >> > server functionality seem enough? > >> >> > > >> >> > Qian > >> >> > > >> >> > > On 8/21/06, Cai Qian wrote: > >> >> > > > Hi, > >> >> > > > > >> >> > > > On 8/21/06, Daniel Jacobowitz wrote: > >> >> > > > > On Sun, Aug 20, 2006 at 10:10:45PM +0100, Cai Qian wrote: > >> >> > > > > > Hi, > >> >> > > > > > > >> >> > > > > > How can I communicate a virtual machine (like Java virtual > >> >> machine) > >> >> > > > > > with the host, If I want to use GDB serial protocol? The > >> >> target > >> >> > > > > > backend has been developed for the virtual machine, so > >> >> simple C code > >> >> > > > > > can be complied and run. In addition, I have written a > >> >> remote stub for > >> >> > > > > > the target. > >> >> > > > > > >> >> > > > > I'm sorry, I don't understand the question. What are you > >> >> trying to do > >> >> > > > > that you don't know how to? Normally the stub and debugger > >> >> would use > >> >> > > > > TCP to communicate, or a pipe. > >> >> > > > > > >> >> > > > > >> >> > > > I tried to use GDB to remote debug code run on virtual machine, > >> >> but I > >> >> > > > don't know how to commnunicate target and host. Does it mean I > >> >> need to > >> >> > > > insert some code to virtual machine, so it will wait a socket > >> >> Then, > >> >> > > > GDB is going to connect this port? > >> >> > > > > >> >> > > > Qian > >> >> > > > > >> >> > > > > -- > >> >> > > > > Daniel Jacobowitz > >> >> > > > > CodeSourcery > >> >> > > > > > >> >> > > > > >> >> > > > >> >> > > >> >> > >> > > >> > >> -- > >> I would remember that if researchers were not ambitious > >> probably today we haven't the technology we are using! > >> > >> > > > > -- > I would remember that if researchers were not ambitious > probably today we haven't the technology we are using! > >