can anyone tell me which function to call to pause the kernel
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 )
Quoted 5 lines · walkerlala
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 don't think you can actually stop the kernel. The linux kernel is multi-threads and events driven, so I doubt you can stop and restart it that easily.
BUT
if you want to interract with userland, you can implement a syscall on your own, or create a proc device (for instance) to let user read / write data to the kernel.
For instance, you could create a proc entry called gettime, and when user reads it (ie: cat /proc/gettime) you would provide a proper answer.
Hope this help.
Fran?ois
Quoted 9 lines · walkerlala
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 )
Quoted 5 lines
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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 :)
Signature · 10 lines
regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20160516/04028e87/attachment.html
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Quoted 47 lines · walkerlala
Quoted 35 lines · Mulyadi Santosa
On Thu, May 12, 2016 at 9:55 PM, walkerlala <[email protected] <mailto:[email protected]>> 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 at kernelnewbies.org <mailto:
Kernelnewbies at kernelnewbies.org>
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbiesHi...
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,Quoted 7 lines
Mulyadi Santosa
Freelance Linux trainer and consultantblog: the-hydra.blogspot.com <http://the-hydra.blogspot.com>
training: mulyaditraining.blogspot.com <
http://mulyaditraining.blogspot.com>Hi, thanks for reply.
Quoted 10 lines
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.
Signature · 10 lines
regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20160517/cd6b9579/attachment.html
Quoted 85 lines · Mulyadi Santosa
On Mon, May 16, 2016 at 7:36 AM, walkerlala <[email protected] <mailto:[email protected]>> wrote:
On 2016?05?16? 01:36, Mulyadi Santosa wrote:
On Thu, May 12, 2016 at 9:55 PM, walkerlala <ablacktshirt at gmail.com <mailto:[email protected]> <mailto:ablacktshirt at gmail.com <mailto:[email protected]>>> 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 at kernelnewbies.org
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbiesHi...
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 consultantblog: 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.
Quoted 8 lines
--
regards,Mulyadi Santosa
Freelance Linux trainer and consultantblog: 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,
Quoted 3 lines · walkerlala
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?
Quoted 6 lines
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.
Quoted 1 line
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.... -------------- next part --------------
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Quoted 30 lines · Valdis.Kletnieks at vt.edu
Quoted 3 lines · walkerlala
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?
Quoted 6 lines
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/Xorgvt2 -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
Quoted 6 lines
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,