an online kernel crash book, and wondering what's deprecated
in my online travels yesterday, i ran across this gem, "Linux Kernel Crash Book": http://www.dedoimedo.com/computers/crash-book.html and am now wondering about what would constitute a reasonable (and minimal?) list of canonical kernel debugging tools. first, while the book above covers Linux Kernel Crash Dump (LKCD), the author freely admits that it's been pretty much obsoleted by the more recent and flexible kdump, so there seems to be little value in digging into LKCD (or, in my case, adding any coverage of it to a kernel debugging course, which i am currently designing). next, someone else's course i'm teaching next week has a kernel debugging chapter which opens with netdump and diskdump before moving onto kdump and kexec, but those earlier utilities are *also* deprecated these days, http://serverfault.com/questions/181554/how-should-i-capture-linux-kernel-pa... so i would be tempted to skip any coverage of netdump and diskdump in favour of additional and more advanced coverage of kdump and kexec. along those lines, i'm just digging into ftrace and was wondering if it in any way obsoleted systemtap, but i've heard from more than one source that while ftrace is allegedly more powerful, systemtap still has its place and is worth talking about. so ... if one was going to put together a (small) toolbox of kernel debugging tools, what's worth covering? interested in any feedback. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================
On Wed, Sep 26, 2012 at 5:03 PM, Robert P. J. Day <rpjday@crashcourse.ca>wrote:
in my online travels yesterday, i ran across this gem, "Linux Kernel Crash Book":
http://www.dedoimedo.com/computers/crash-book.html
and am now wondering about what would constitute a reasonable (and minimal?) list of canonical kernel debugging tools.
first, while the book above covers Linux Kernel Crash Dump (LKCD), the author freely admits that it's been pretty much obsoleted by the more recent and flexible kdump, so there seems to be little value in digging into LKCD (or, in my case, adding any coverage of it to a kernel debugging course, which i am currently designing).
next, someone else's course i'm teaching next week has a kernel debugging chapter which opens with netdump and diskdump before moving onto kdump and kexec, but those earlier utilities are *also* deprecated these days,
http://serverfault.com/questions/181554/how-should-i-capture-linux-kernel-pa...
so i would be tempted to skip any coverage of netdump and diskdump in favour of additional and more advanced coverage of kdump and kexec.
along those lines, i'm just digging into ftrace and was wondering if it in any way obsoleted systemtap, but i've heard from more than one source that while ftrace is allegedly more powerful, systemtap still has its place and is worth talking about.
so ... if one was going to put together a (small) toolbox of kernel debugging tools, what's worth covering? interested in any feedback.
rday
--
======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca
Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================
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Hi Robert, Good to know that you are preparing material. For linux kernel debugging, I would love if you could include, kdb, kgdb and also their setup environment, like now most people do development on Virtual Machine. So the debugger needs to be setup on the VM and its serial port to the host machine, where the debugging logs would be displayed. - Rohan
Hi Rob... On Wed, Sep 26, 2012 at 6:33 PM, Robert P. J. Day <rpjday@crashcourse.ca> wrote:
along those lines, i'm just digging into ftrace and was wondering if it in any way obsoleted systemtap, but i've heard from more than one source that while ftrace is allegedly more powerful, systemtap still has its place and is worth talking about.
since systemtap is still included in Redhat Enterprise Linux, I could firmly say SystemTap is still highly relevant these days. So is kdump/kexec.
so ... if one was going to put together a (small) toolbox of kernel debugging tools, what's worth covering? interested in any feedback.
IMHO, the most important part is the art of understanding oops message and its related stack trace. Or worst, what if the system just hangs....divide and conquer things like disabling acpi, sysrq, might be the skills we need here. Not sure if you agree with me here, but I just deliver my ideas. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
On Wed, Sep 26, 2012 at 8:11 PM, Mulyadi Santosa <mulyadi.santosa@gmail.com>wrote:
Hi Rob...
On Wed, Sep 26, 2012 at 6:33 PM, Robert P. J. Day <rpjday@crashcourse.ca> wrote:
along those lines, i'm just digging into ftrace and was wondering if it in any way obsoleted systemtap, but i've heard from more than one source that while ftrace is allegedly more powerful, systemtap still has its place and is worth talking about.
since systemtap is still included in Redhat Enterprise Linux, I could firmly say SystemTap is still highly relevant these days. So is kdump/kexec.
so ... if one was going to put together a (small) toolbox of kernel debugging tools, what's worth covering? interested in any feedback.
IMHO, the most important part is the art of understanding oops message and its related stack trace.
I agree :)
Or worst, what if the system just hangs....divide and conquer things like disabling acpi, sysrq, might be the skills we need here.
Not sure if you agree with me here, but I just deliver my ideas.
-- regards,
Mulyadi Santosa Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
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- Rohan
On Wed, Sep 26, 2012 at 8:33 AM, Robert P. J. Day <rpjday@crashcourse.ca> wrote:
in my online travels yesterday, i ran across this gem, "Linux Kernel Crash Book":
http://www.dedoimedo.com/computers/crash-book.html
and am now wondering about what would constitute a reasonable (and minimal?) list of canonical kernel debugging tools.
first, while the book above covers Linux Kernel Crash Dump (LKCD), the author freely admits that it's been pretty much obsoleted by the more recent and flexible kdump, so there seems to be little value in digging into LKCD (or, in my case, adding any coverage of it to a kernel debugging course, which i am currently designing).
next, someone else's course i'm teaching next week has a kernel debugging chapter which opens with netdump and diskdump before moving onto kdump and kexec, but those earlier utilities are *also* deprecated these days,
http://serverfault.com/questions/181554/how-should-i-capture-linux-kernel-pa...
so i would be tempted to skip any coverage of netdump and diskdump in favour of additional and more advanced coverage of kdump and kexec.
along those lines, i'm just digging into ftrace and was wondering if it in any way obsoleted systemtap, but i've heard from more than one source that while ftrace is allegedly more powerful, systemtap still has its place and is worth talking about.
While learning ftrace I found there's little good documentation for ftrace. Ftrace is huge and very flexible, you can do lot more than just trace your functions. I firmly believe ftrace + perf should be consider like a serious debugging technique. Regards, Ezequiel.
participants (4)
-
Ezequiel Garcia -
Mulyadi Santosa -
Robert P. J. Day -
Rohan Puri