Re: can anyone tell me which function to call to pause the kernel
On Mon, May 16, 2016 at 7:36 AM, walkerlala <ablacktshirt@gmail.com> wrote:
On 2016年05月16日 01:36, Mulyadi Santosa wrote:
On Thu, May 12, 2016 at 9:55 PM, walkerlala <ablacktshirt@gmail.com <mailto:ablacktshirt@gmail.com>> wrote:
I successfully insert some function into the kernel code and make it execute when the kernel start up, but I just can't make the kernel stop executing. Are there any functions which can pause the kernel so that I prompt the user, and let the user input a command(maybe a comment to display the current time. Something like a shell would do) and interact ? (I had checked the "sys_***" functions in this page: http://docs.cs.up.ac.za/programming/asm/derick_tut/syscalls.html but just can't find a proper one )
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Hi...
sounds like what kgdb does. But not sure if it is still maintained or not.
btw, kernel can not be paused, actually. if you really need that, you need to run linux kernel inside virtual machine and pause the virtual machine. But doing that, you will also pause user space too :)
-- regards,
Mulyadi Santosa Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com <http://the-hydra.blogspot.com> training: mulyaditraining.blogspot.com < http://mulyaditraining.blogspot.com>
Hi, thanks for reply.
I know using a debugger or virtual machine would help a little bit, but that's not interactive any more. What I want is just a shell-like "interactive" kernel (may be I am a little naive to think that ?)
Why the kernel cannot be stopped ? I think, now that if the kernel can be interrupted, then why can't it be stopped by some mechanisms ?
Regards,
Hi... please add kernelnewbies to cc: list too next time :) Kernel can't be stopped, because it's actually servicing event mostly generated by hardware (interrupts etc) or user space (syscall etc). So unless you stop these two aspects to raise events, basically kernel will still do its works. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
On 2016年05月17日 19:41, Mulyadi Santosa wrote:
On Mon, May 16, 2016 at 7:36 AM, walkerlala <ablacktshirt@gmail.com <mailto:ablacktshirt@gmail.com>> wrote:
On 2016年05月16日 01:36, Mulyadi Santosa wrote:
On Thu, May 12, 2016 at 9:55 PM, walkerlala <ablacktshirt@gmail.com <mailto:ablacktshirt@gmail.com> <mailto:ablacktshirt@gmail.com <mailto:ablacktshirt@gmail.com>>> wrote:
I successfully insert some function into the kernel code and make it execute when the kernel start up, but I just can't make the kernel stop executing. Are there any functions which can pause the kernel so that I prompt the user, and let the user input a command(maybe a comment to display the current time. Something like a shell would do) and interact ? (I had checked the "sys_***" functions in this page: http://docs.cs.up.ac.za/programming/asm/derick_tut/syscalls.html but just can't find a proper one )
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org <mailto:Kernelnewbies@kernelnewbies.org> <mailto:Kernelnewbies@kernelnewbies.org <mailto:Kernelnewbies@kernelnewbies.org>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Hi...
sounds like what kgdb does. But not sure if it is still maintained or not.
btw, kernel can not be paused, actually. if you really need that, you need to run linux kernel inside virtual machine and pause the virtual machine. But doing that, you will also pause user space too :)
-- regards,
Mulyadi Santosa Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com <http://the-hydra.blogspot.com> <http://the-hydra.blogspot.com> training: mulyaditraining.blogspot.com <http://mulyaditraining.blogspot.com> <http://mulyaditraining.blogspot.com>
Hi, thanks for reply.
I know using a debugger or virtual machine would help a little bit, but that's not interactive any more. What I want is just a shell-like "interactive" kernel (may be I am a little naive to think that ?)
Why the kernel cannot be stopped ? I think, now that if the kernel can be interrupted, then why can't it be stopped by some mechanisms ?
Regards,
Hi...
please add kernelnewbies to cc: list too next time :)
Kernel can't be stopped, because it's actually servicing event mostly generated by hardware (interrupts etc) or user space (syscall etc). So unless you stop these two aspects to raise events, basically kernel will still do its works.
-- regards,
Mulyadi Santosa Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com <http://the-hydra.blogspot.com> training: mulyaditraining.blogspot.com <http://mulyaditraining.blogspot.com>
Can I just disable interrupts from hardwares? I know that, at the very beginning, the kernel disable interrupt for convenient. So I wonder whether we can do thing like this. Put it in another way: when we "interact" with a Linux Desktop, there are also many programs running underneath as daemons, but we can still do our own works without even noting their existing. So I wonder, is there a similar way that we can use to interact with the kernel (without using a debugger) ? If there is, can you any one show me some examples ? Thanks in advance Regards,
On Tue, 17 May 2016 20:29:12 +0800, walkerlala said:
Can I just disable interrupts from hardwares? I know that, at the very beginning, the kernel disable interrupt for convenient. So I wonder whether we can do thing like this.
Sure you can do that. But then, how do you get the kernel's attention?
Put it in another way: when we "interact" with a Linux Desktop, there are also many programs running underneath as daemons, but we can still do our own works without even noting their existing. So I wonder, is there a similar way that we can use to interact with the kernel (without using a debugger) ?
Try this: Start up Xorg and your preferred window manager. Open an xterm or a Gnome-terminal or whatever.
From that window, try to attach gdb to the Xorg process:
% ps ax|grep Xorg 1791 tty2 S+ 69:42 /usr/libexec/Xorg vt2 -displayfd 3 -auth /run/user/967/gdm/Xauthority -nolisten tcp -background none -noreset -keeptty -verbose 3 62036 pts/0 S+ 0:00 grep Xorg % gdb -p 1791 What happens? Why does it happen? Eventually, you'll figure out what Xorg and the kernel have in common here....
On 2016年05月17日 23:21, Valdis.Kletnieks@vt.edu wrote:
On Tue, 17 May 2016 20:29:12 +0800, walkerlala said:
Can I just disable interrupts from hardwares? I know that, at the very beginning, the kernel disable interrupt for convenient. So I wonder whether we can do thing like this.
Sure you can do that.
But then, how do you get the kernel's attention?
Put it in another way: when we "interact" with a Linux Desktop, there are also many programs running underneath as daemons, but we can still do our own works without even noting their existing. So I wonder, is there a similar way that we can use to interact with the kernel (without using a debugger) ?
Try this:
Start up Xorg and your preferred window manager.
Open an xterm or a Gnome-terminal or whatever.
From that window, try to attach gdb to the Xorg process:
% ps ax|grep Xorg 1791 tty2 S+ 69:42 /usr/libexec/Xorg vt2 -displayfd 3 -auth /run/user/967/gdm/Xauthority -nolisten tcp -background none -noreset -keeptty -verbose 3 62036 pts/0 S+ 0:00 grep Xorg % gdb -p 1791
What happens?
Why does it happen?
Eventually, you'll figure out what Xorg and the kernel have in common here....
Ok after trying what you said, I think I understand what you mean eventually. I try to use gdb to attach the window manager, which happen to be Compiz on my machine, then the whole GUI block. The only thing that I can see being able to react is the cursor(honestly I don't understand why the cursor can move....) This is my reasoning: when I attach gdb to Compiz, the window manager block, thus not being able to serving. The same with the kernel. If I block the kernel, then it would not be able to serve..... Is this what you mean ? So I have to wait for the kernel to finish and prompt me a console ? Actually, I am willing to do so, but I just can't get the raw kernel to run at Qemu. That is the reason why I tried to block the kernel...... Any idea ? Regards,
participants (3)
-
Mulyadi Santosa -
Valdis.Kletnieks＠vt.edu -
walkerlala