I want to write my own hypervisor for Intel Platform based on an open project and I want understand how to debug it.
I have real stend to debug on, but it reboots at faults and it is hard to find mistake. I've found I could use QEMU/KVM with nested hypervisor to debug it. May be there are any other variants? VMware is hanging with faults, as I understand. On AMD platforms I have used SimNow.
It will be good if the host system will be Windows.
Thank you for advices.
It depends on your flavor. The couple Qemu/GDB is a good start. Here are some useful hints if your host platform is Intel CPU, you can:
start qemu like this : qemu-system-x86_64 -enable-kvm -cpu host -s -S .... Qemu will boot the hypervisor along with its gdbserver and pause it until it receives continue command from gdb.
Start GDB like this: gdb /path/to/hypervisor then, target remote :1234 to attach the gdb to the gdbserver
Use hbreak instead of break, but you have only 4 breakpoints left
From this point, you may continue the debugging as for a simple application
Related
I'm trying to use GDB to debug Qemu running on m68k architecture. I am attempting to make some changes to Qemu source to add some functionality to m68k support, and I am trying to use GDB to test changes I have currently made. Important to note is that I am using Qemu v5.2.0-rc1, as that is the version of Qemu currently utilized in a larger system that I am concurrently working with. Currently, I am using qemu-system-m68k to run buildroot (uClinux kernel) on that architecture, using the "-s -S" options for gdb. In a separate terminal, I am trying to run GDB on that remote target using (gdb) target remote localhost:1234, but I am getting the following error message:
warning: Architecture rejected target-supplied description
The connection to the uClinux Qemu kernel seems to go okay, but I cannot connect to the remote host.
I have tried finding any possible solutions to this problem, including setting the GDB architecture (currently says i386, not sure if this is right), which does not work. I have no idea how to get GDB running on this m68k Qemu emulated Linux kernel, and any help would be great. Thanks!
The error message means that QEMU's gdb stub sent gdb a description of what the CPU is (mostly a list of registers), and gdb didn't understand it. One common cause of this is trying to debug with a gdb for the wrong architecture.
You need to use a gdb which is aware of the the target architecture. On Ubuntu there is a 'gdb-multiarch' package which has a gdb-multiarch binary that knows about more than just x86. Otherwise you might need to build gdb from source. You can check if your gdb knows about m68k by running it with no arguments and typing the command set arch m68k. If it replies The target architecture is assumed to be m68k then it's OK (and your issue is something more complicated); if it gives you an error (eg Undefined item: "m68k") then you need to use a different gdb.
I am debugging a remote target and it seems like the software breakpoints are not working, however hardware breakpoints do work.
I want to be able to use the stepi command - but gdb seems to insist on using software breakpoints.
Is there a way to force gdb to use hardware breakpoints for stepi?
The target is an ARM STM32 chip debugged through a blackmagic probe.
One solution is to mark the memory region as read only which forces gdb to use hw breakpoints
I.e if my code is running on the addresses 0x8000000-0x8010000 i run
mem 0x8000000 0x8010000 ro
I want to setup the following environment: I've got a STM32H753I-EVAL2 eval board, connected on a Windows PC. Until now I was developping and debugging locally on this PC with STM32CubeIDE. For several reasons my code source is on a Linux server (Samba mounting) so it takes forever to build a project. Hence I want to develop on the linux server from my Windows machine.
Compiling is working fine (and is way faster) but the issue is about debugging. I know it is possible to debug remotely, the Debug Configuration window from Eclipse (I'm using OpenOcd) allows to connect to a remote GDB server. What I don't know is how to start a GDB server on the Windows machine that will connect to the STM32 board ?
Sorry for the "answer to myself" but I think it might be useful for others (and even to me when I have forgotten in a few weeks ;) ).
Here is how to do.
on host side (on the machine where the eval board is physically plugged in) you have to manually launch the GDB server application that comes with STM32CubeIDE installation. See STMicro application note UM2576 for details. The default command line is:
ST-LINK_gdbserver.exe -d -v -cp "C:\ST\STM32CubeIDE_1.0.0.19w12patch\STM32CubeIDE\plugins\com.st.stm32cube.ide.mcu.externaltools.cubeprogrammer.win32_1.0.0.201903011553\tools\bin"
Now you've done the hardest. On server/remote side you have to setup the Debug Configuration to use OpenOcd with option "Connect to remote GDB server" and simply enter IP address and port number (which is not 3333 by default but 61234, but it can be modified).
This setup is working fine, even if I encoutered some instabilities during debugging once in a while.
I see two (maybe three) options
Use an alternate GDB server (see below)
Run the GDB server from STMCubeIDE in isolation (see OP's answer for Windows, this answer for Linux)
GDB Serial (not really an option right now but I'll share my experience so far)
I have used the second option to succesfully debug my target using arbitary GDBs such as gdb-multiarch command line and in the (non STMCube-ified) Eclipse CDT
Alternative GDB Servers
You could try STLink open source. I did. The problem is, your device might not be supported properly. I built 1.6.1 from Github to enable support for STM32G03x device. While moving to this version enabled it to detect the device, and I can use st-flash to program the device, the debugger is unusable (try and alter a register, it alters the wrong one, try and single step a program, it crashes immediately).
Do try it though .. it's easy and quick to install (or build), so it's worth checking if your device will work correctly with it.
Openocd is another option, but seems not to support SWD connection. I tried a build that allegedly had a patch for this but no luck.
If you can get one of these open source alternatives to work, they have another advantage, you may be able run them on something like a Raspberry PI, which means you don't have to get a PC physically close to your target.
Run the GDB server from STMCubeIDE in isolation
For Windows, see the OP's answer. For Linux, I do this alter the pathnames to suit your installation
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/user/apps/st/stm32cubeide_1.5.1/plugins/com.st.stm32cube.ide.mcu.externaltools.stlink-gdb-server.linux64_1.5.0.202011040924/tools/bin/native/linux_x64/ /home/user/apps/st/stm32cubeide_1.5.1/plugins/com.st.stm32cube.ide.mcu.externaltools.stlink-gdb-server.linux64_1.5.0.202011040924/tools/bin/ST-LINK_gdbserver -p 61234 -l 1 -d -s -cp /home/user/apps/st/stm32cubeide_1.5.1/plugins/com.st.stm32cube.ide.mcu.externaltools.cubeprogrammer.linux64_1.5.0.202011040924/tools/bin -m 0 -k
How did I get to this? Firstly launched a debugging session from STMCubeIDE, then ran
ps aux | grep gdbserver
Then we can see how Eclipse (STMCube) is launching the gdbserver and work from there.
If you find it complains about a .so file, locate that file from the STMCube installation and ensure the path to the directory containing it is in LD_LIBRARY_PATH (as per my example)
You can also launch the program with --help to show more options.
If add -e (persistent) you can disconnect and reconnect a GDB client without resetting the target (it will reset on initial invocation of the gdb server though, even without -k).
GDB Serial
This is where the target implements the GDB server end of the protocol. The GDB stub usually runs in an exception handler. This would usually be your breakpoint handler but you can also make it the default handler for unhandled exceptions, or, for example, the ctrl-c interrupt.
I have done a lot of Googling about this recently and basically when people ask about it on forums they usually get responses along the lines of "Here be dragons" or "Why don't you use JTAG?"
So the drivers for this, you might like to know, are in the GDB sources git://sourceware.org/git/binutils-gdb.git under gdb/stubs. The documentation is here. There isn't a stub implementation there for arm. Which is sad really, I used to use GDB remote serial regularly where I worked, and some of those targets were indeed ARM. The operating system was ecos.
So could ecos GDB stubs be ported to bare metal? Having giving it a good coat of looking at, I believe yes they could. The stubs are based on the ones from the GDB sources but they are heavily polluted with Ecos and Redboot build macros and copyright (the ogiringals were written by HP and released without copyright). We don't know what bugs the Ecos stubs may contain (I fixed at least one back in the day and I don't recall whether I submitted a patch). We don't know if they really support the latests architectures properly. And, we don't know if, after that, they simply use up too much memory - my STM32 has 8K of SRAM and I already see buffers that have a default size of 2K (not saying that's necessary but you see how work needs to be done here..)
So this third option, I will revisit this one day but for now, for me, it's a nope.
I've just spent a whole day trying to find a way to enable GDB debugging from Qt Creator or Eclipse. I learned that there are basically two approaches to launch the target application:
Using ssh (ssh host gdb)
Using gdbserver
I was able to use both approaches to launch gdb remotely and start the application. However, GDB never responds to any breakpoints set in the IDE. Also I can't pause the application to inspect the program state. In Qt Creator I just get an obscure stack trace (I might have been looking at the traces of ssh or gdb actually...).
Can anyone help me to get started?
Progress!
I found that with Qt Creator 2.0 there is an feature called "Attach and debug remote application." It's based on gdbserver. The good thing is that it stops on the IDE's breakpoints. However, there are two issues:
When it hits a breakpoint it only shows assembly code, not the source code.
GDB often quits because of 'signal received'
I should probably mention that the remote executable is compiled with an older version of GCC than the one installed on my local PC. Perhaps some of the problems are related to this.
Update
I should mention that I switched to running cgdb on the remote machine via SSH.
The remote Qt Creator-based solution wasn't stable. GDB tends to quit because of mysterious 'signal received' messages.
So that GDB on your host (the machine you develop and compile on, so where you have Qt Creator) you have to give it access to the "symbol file".
I usually don't use Qt Creator, but GDB and gdbserver directly for cross-compiled programs remote-debugging. You could maybe give this a try to be sure that this works for you and maybe then find the missing option in Qt Creator (or maybe this will help you find what is missing).
On the target machine run:
gdbserver :5000 yourprogram
On the host machine, run gdb and then load the symbol file:
(gdb) symbol-file yourprogram
On GDB on the host machine, you then have to connect to connect GDB to the remote gdbserver:
(gdb) target remote target_ip_address:5000
From then you can use GDB on the host controlling the program on the target.
I hope this helps!
Due to peculiarities in our makefile build system the file references contained in the debugging symbols look like this:
../src/main.cpp
../../src/utils/logger.cpp
This is no problem for GDB, but Qt Creator was unable to map these paths to the actual files. I was able to fix this by adding 'dir' statements in the GDB init file:
dir src
dir src/utils
...
Now it works.
We're using the Eclipse CDT 5 C++ IDE on Windows to develop a C++ application on a remote AIX host.
Eclipse CDT has the ability to perform remote debugging using gdbserver. Unfortunately, gdbserver is not supported on AIX.
Is anyone familiar with a way to debug remotely using Eclipse CDT without gdbserver? Perhaps using an SSH shell connection to gdb?
finally I got gdb run remotly anyhow now. At the Bug-symbol on the taskbar I took Debug Configurations - GDB Hardware Debugging.
In Main C/C++ Applications I set the full path on the Samba share of the executable (X:\abin\vlmi9506). I also set a linked folder on X:\abin in the project. Then I modified my batch-script in GDB Setup. It's not directly calling gdb in the plink-session but a unix-shell-script, which opens gdb. By this I have the possibility to set some unix environment-variables for the program before doing debug. The call in my batch:
plink.exe prevoax1 -l suttera -pw XXXXX -i /proj/user/dev/suttera/vl/9506/test/vlmi9506ddd.run 20155 dev o m
In the unix script I started gdb with the command line params from eclipse, that I found in my former tryals. The call in the shell command looks like this:
gdb -nw -i mi -cd=$LVarPathExec $LVarPathExec/vlmi9506
Then IBM just gives gdb 6.0 for AIX. I found version 6.8 in the net at http://www.perzl.org/aix/index.php?n=Main.Gdb. Our Admin installed it.
I can now step through the program and watch variables. I even can write gdb-commands directly in the console-view. yabadabadooooooo
Hope that helps to others as well. Can not tell, what was really the winner-action.
But each answer gives more new questions. Now I got 3 of them.
When I start the debug config I have to click restart in the toolbar to come really in the main procedure. Is it possible to come directly in main without restarting?
On AIX our programs are first preprocessed for embedded sql. The preprocessed c-source is put in another directory. When I duble-click the line to set a breakpoint, I get the warning "unresolved breakpoint" and in the gdb-console I see, that the break is set to the preprocessed source which is wrong. Is it possible to set the breakpoints on the right source?
We are using CICS on AIX. With the xldb-Debugger and the CDCN-command of CICS we manage that debugging is started, when we come in our programs. Is it possible to get that remotely (in plink) with gdb-eclipse as well?
I wouldn't normally take a shot in the dark on a question I can't really test the answer to, but since this one has sat around for a day, I'll give it a shot. It seems from looking at:
http://wiki.eclipse.org/TM_and_RSE_FAQ#How_can_I_do_Remote_Debugging_with_CDT.3F
...that even if the CDT has changed since that wiki page was made, you should still be able to change the debug command to:
ssh remotehost gdb
instead of using TM which uses gdbserver. This will probably be slightly slower than the TM remote debugging since that actually uses a local gdb, but on the other hand this way you won't have to NFS or SMB mount your source code to make it available to the local debugger (and if you're on a LAN it probably won't matter anyhow).
There's also a reference TCF implementation for linux, which you may or may not have any luck recompiling for AIX, but it allows for remote debugging if gdbserver is otherwise not available:
http://wiki.eclipse.org/DSDP/TM/TCF_FAQ
tried also to remotly debug an aix-appl with windows eclipse-cdt-gdb.
Got blocked at the end with unix/windows path-problems. Maybe my result can help u a little further - maybe you already got it work. I'm interested in your comment. asked on eclipse news portal- following the answer of martin oberhuber (thanks again) tried dsp dd (also blocked with path problem) and set an request in eclipse bugzilla.
here the link to news:
http://www.eclipse.org/newsportal/article.php?id=406&group=eclipse.dsdp.tm
Here my bugzilla:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=252758
At the moment we still debug localy with xldb but I am trying ddd-gdb at the moment. At least locally gdb is running.