Im using ARMv7 as a target machine. I have compiled the Linux source 2.6.34.13 for target.
Target is connected with Host(Linux Development machine) through serial port using minicom.
Target is loaded with new kernel and KGDB is enabled in command prompt.
$ echo ttyAMA0 > /sys/module/kgdboc/parameters/kgdboc
$ echo g > /proc/sysrq-trigger
Entering KGDB... message is displayed and waits for commands.
In Host side,
$arm-none-linux-gnueabi-gdb vmlinux
gdb > set remotebaud 115200
gdb > set debug remote 1
gdb > target remote /dev/ttyS0
After this, some command communication takes place by default.
qSupported is sent from Host to Target. But qSuppoted is not supported by target so $#00 is returned. similarly ?, HC-1 commands were sent but receives proper response.
But qOffsets command not receiving any response from target.
I suspect vmlinux. Because if I give list in gdb, its not showing 10 lines of code instead it says
arch/arm/kernel/head.S : No such file or directory.
Note :: Kernel compilation done in server. so no source is available in development machine. But arm-gdb looks for head.S it seems.
I am not sure what mistake im doing. I need symbols to be loaded for entire kernel. Guide me in this regards.
That kgdb is looking for head.S is not an error. If you look here you will see that there is a head.S file in the source tree. It's an assembler file that's all. There are several source files written in assembler for this platform.
It is normal, because some instructions especially boot sequences and other "low-level" functionalities are written in assembler because it is easier.
As written in the comments already, gdb needs the sources to browse them while debugging. In the debug-sections, which contain the debug-symbols and are generated when running gcc with -g, there are "only" references to the source-file and line and column, amongst others. See here for more information and further links about debug-symbols with gcc.
That kgdb is looking for head.S is a good sign that you're doing things right. If you have the sources available (and it can be as simple as untarring the tarball of the right version) just run kgdb inside this source-tree or use the -d argument to add source-search-path, being on your development machine of course.
Finally Host to Target communication established just bcos of line delay. There is no relationship between kernel source in development machine and time-out issues.
For the time-out kind of issue for some of the commands say qOffset and qSupported is solved by using GtkTerm instead of minicom as the serial port communication tool.
Difference is "line delay" option in GtkTerm. so when this is configured to ~250, there is no timeout message thereafter. simply connection established and waits at default break point. If anyone knows how to give this "line delay" in minicom will be more helpful to everyone.
yes ofcourse, we need source code for list command to execute. but without those source also, we can debug i.e si, bt can be executed with the help of vmlinux and system.map.
Note:: set debug remote 1 is not necessary. This gives detailed display of host to command communications. For more detailed view, set debug serial 1.
Related
I've installed gdb and gdbserver on an angstrom linux ARM board (with external access), and am trying to get source level debugging of a shared library working from my local machine. Currently, if I ssh into the device, I can run gdb and I am able to get everything working, including setting a breakpoint, hitting it and doing a backtrace.
My problem comes when I try and do the same using gdbserver and running gdb on my host machine in order to accomplish the same thing (eventually I'd like to get this working in eclipse, but in gdb is good enough for the moment).
I notice that when I just use gdb on the server and run "info shared", it correctly loads symbol files (syms read : yes for all), which I'm then able to debug. I've had no such luck doing so remotely, using "symbol-file" or "directory" or "shared". Its obviously seeing the files, but I can't get it load any symbols, even when I specify remote files directly. Any advice on what I can try next?
There are a few different ways for this to fail, but the typical one is for gdb to pick up local files rather than files from the server.
There are also a few different ways to fix this, but the simplest by far is to do this before invoking target remote:
(gdb) set sysroot remote:
This tells gdb to fetch files from the remote system. If you have debug info there (which I gather from your post that you do), then it will all work fine.
The typical problem with this approach is that it requires copying data from the remote. This can be a pain if you have a bad link. In this case you can keep a copy of the data locally and point sysroot at the copy. However, this requires some attention to keeping things in sync.
First run up to main, and then set solib-search-path . Otherwise, gdbserver stops in the dynamic loader, before libraries can be loaded. More details at: Debugging shared libraries with gdbserver
im making a C project for university in Linux, its basicaly a protocol for file transfer between 2 computers. The program works fine and it sends many files without any problem, but there is 1 or 2 files i have tested and the program just crashes without any report and i just dont know how to debug the problem. Any help would be appreciated.
I also dont know if i should post the code or not, because both files (application and protocol) have over 1.5k lines of code.
In most Linux Distributions the core dumping is disable by default (which can be viewed from the system resource limit "ulimit -c" will be zero if it is disabled). To enable the same, use "ulimi -c unlimited".
To add, in Ubuntu like modern distributions, they have customized program to send the report/core file to Ubuntu developers specified in "/proc/sys/kernel/core_pattern". Make sure to change it for development purpose to debug further.
You can even try "valgrind" or "gdb live debugging" to have more clarity about the problem.
I have an exam on tomorrow on TCP/IP programming. Following is one of the previous question on this paper.
Write and run a client and a server program. Using C language in UNIX, with the
following specifications :
• A TCP client program will send a range of number (e.g. 1 to 10) to the server.
• TCP server accept the number range from client and send back the sum of the
number range. Client will print the result.
I dont know how to setup the compiler and other settings to run this tcp ip programs. When I search online, I got two different programs, one for Client and another For server. Some please tell me how can i run these programs to get desired output. What kind of compiler should I install on my system.( I am using windows 7) ??
Since the assignment requires your code to work on a Unix system, you first need to install one. Follow these simple steps to install a virtual Unix environment on top of your existing Windows installation.
Download and install VirtualBox for Windows.
Download & unpack this Ubuntu 12.10 disc image (NOTE: Requires 7-Zip).
Launch VirtualBox and create a new Virtual Machine (name it Ubuntu).
In the "Virtual Hard Disk" settings, select "Use existing hard disk" and select the image file you just downloaded (NOTE: It's filename should end in ".vdi").
Run your new Virtual Machine. You should see the Ubuntu splash screen.
Login with username ubuntu and password reverse (NOTE: Case Sensitive!).
Open up Terminal and type sudo apt-get install build-essential (NOTE: when Terminal prompts you for a password, use reverse).
You should (with hope) have everything you need for your assignment. For more information on network programming, consult Beej's Guide to Network Programming -- Using Internet Sockets.
You need to open two different terminals on your system.
In the first terminal compile and run the server.c program.(make sure either you listen to all ips or your host ip(atleast).
while this is running.(it will wait for a request from your client program)
Run the client program in the other terminal.
Hope this solves the problem!
For details on how to create and run a file in unix refer http://www.wikihow.com/Compile-a-C-Program-Using-the-GNU-Compiler-%28GCC%29
P.S: you can do the same in win7 if iam not wrong only that terminal here in called command prompt!
Post the results if possible!
Download a thing called VMWare player. And look for a Ubuntu image that you can load with the VMWare player. That way, you will have a little Linux virtual machine that you can run inside or along with Windows 7. You can use the compiler GCC in your Ubuntu or whatever other Linux virtual machine. And get lots of coffee. Blargle is correct, but I think my suggestion is a little better, because you end up having a fairly complete Unix type environment to develop in. Blargle's way put Unix tools on top of Windows, which I find to be kind of clunky.
I learnt socket programming from this site. He has given everything in detail . Download an Vmware workstation and load up ubuntu . Understand the programs they are pretty much straight forward .
Maybe you can try to look at Network Socket on the web. You can easily find a lot of good tutorial that can answer your question.
You can use the compiler you want on your system, depending on what are you using now.
how to get harddrive serial number(not the volume # wich change at each reinstall of windows) in C or asm, without wmi (cause wmi required admin right). Any clue would be helpfull cause right now i found nothing on web in C without wmi, in dayss of searching... Thank you.
EDIT : For windows system
Please try my open source tool, DiskId32, which also has the source code at http://www.winsim.com/diskid32/diskid32.html . I only have an Win32 version at this time. Maybe some day I will add a Win64 version.
Hard drive serial number and other information about the harddrive like firmware version, etc. can only be obtained using SMART as far as I know and that requires special ioctls to the the block device node (/dev/sda or /dev/sdb) which is usually not available to a regular user.
I know there is a tool called smartctl which does exactly this:
sudo smartctl -i /dev/sda
Similar tools exist (hdparm, lshw, etc.) as well.
As far as trying to figure it out this info without being a privileged user, it might be possible only if it is exposed via /proc or /sys which I highly doubt is being done in the current SATA block device drivers.
I cross-compiled NET-SNMP 5.7.1 from sources to a PowerPC using ELDK-3.1.
When I try to load the snmpd daemon in my embedded board, I see the message:
# snmpd -f -Lo
pcilib: Cannot open /proc/bus/pci
pcilib: Cannot find any working access method.
Of course my PPC board has no PCI, and I wonder why is netsnmp looking for it.
In more than one place I see this same message (sourceforge, mail-archive, google-groups), but ir has no answer at all. Another variant, with a little but unhelpful responses at (archlinuxarm).
Can anybody please help me?
I'm assuming you're on a Linux target.
Net-SNMP's changelog lists "[PATCH 3057093]: allow linux to use libpci for creating useful ifDescr strings".
The configure script will search for an available libpci, and, having found one, will define
HAVE_PCI_LOOKUP_NAME and HAVE_PCI_PCI_H. To disable this code: after configuring, you can change those defines in include/net-snmp/net-snmp-config.h, then rebuild. The affected code is in agent/mibgroup/if-mib/data_access/interface_linux.c.
There's also a patch in this bug report: http://sourceforge.net/p/net-snmp/bugs/2449/
I resolved the issue using the stock snmpd that comes with the Raspbian.
In /etc/snmp/snmpd.conf file I isolated the issue to the following line
agentAddress udp:161,udp6:[::1]:161
Instead of listening on all interfaces, if I specify the the ip address of the eth0 interface i.e.:
agentAddress udp:10.0.1.5:161,udp6:[::1]:161
Then snmpd starts fine.
My speculation is that the stock snmpd tries to enumerate all possible interfaces including the pci ones.