----- Original Message ----- > > > Hi Dave, > > > please find my comments below. > > Dave: If a breakpoint were set, it would > generate an interrupt in the kernel, control would be passed > to an interrupt handler, and any "work" would have to be done > there (within the context of the interrupt handler) since the > crash utility code could not run in user-space. > > Oza: yes, but not necessarily it has to be done in interrupt context, > but signal could be sent to crash may be SIGTRAP or something. > the whole kernel preemption could be disabled the moment the signal > is delivered and whole kernel freezes and control always stay with > crash utility. where you could inspect kernel datastructures at > break-pointed kernel. > > I could be easily missing many things over here, as it is also just a > thought from my side without detailed thinking. > of course on SMP; things become even more complex > > and I even do not know the cost vs benefit ratio here. > > Dave: The crash utility has never done such a thing since its inception > in early UNIX. And yes, kgdb, kdb, kprobes, ftrace, or systemtap > would be more in line with what you're looking for. > > Oza: > > kgdb doesnt seem to be inline anymore with kernel versions. > kdb, you need recompilation of kernel, and I am not sure it supports > ARM and symbols, it seems to be working with raw addresses. > ftrace is again tracing mechanism, I am not sure it supports > breakpoints and watchpoint, of course you can debug the kernel but > in a different way. systemtap is again having tracing capabilities. I'm not sure what you mean by that -- systemtap is far more than a tracer. You can write very involved handlers to run when the breakpoint is hit. > I could be easily wrong in thinking that crash could suport > breakpoints and watchpoints, and I could be easily underestimating > the capabilities of the tools you have mentioned; > > but I thought technically it might be feasible to incorporate > breakpoint support in crash. You're on your own... Dave -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility