Hi Andrew, On 6 January 2015 at 05:44, Andrew Morton <a...@linux-foundation.org> wrote: > On Tue, 23 Dec 2014 18:08:29 +0530 Kiran Raparthy <kiran.ku...@linaro.org> > wrote: > >> From: Colin Cross <ccr...@android.com> >> >> debug: prevent entering debug mode on panic/exception. >> >> On non-developer devices, kgdb prevents the device from rebooting >> after a panic. >> >> Incase of panics and exceptions, to allow the device to reboot, prevent >> entering debug mode to avoid getting stuck waiting for the user to interact >> with debugger. >> >> To avoid entering the debugger on panic/exception without any extra >> configuration, panic_timeout is being used which can be set via >> /proc/sys/kernel/panic at run time and CONFIG_PANIC_TIMEOUT sets the default >> value. >> >> ... >> > > hm. Why overload the meaning of panic_timeout in this fashion? If > someone is using kgdb and has panic_timeout set, they'll get quiet a > surprise. We are just using already exported kernel symbol to avoid extra configuration. So we have chosen panic_timeout to allow kgdb to honor CONFIG_PANIC_TIMEOUT. I can modify the commit text if you feel the above commit text overloading the meaning of panic_timeout.
To give you a better idea about why we have used panic_timeout, sharing Daniel's previous review comment: "It ought to be possible for kgdb/kdb to honour CONFIG_PANIC_TIMEOUT by tracking how long it takes for the user to attach a debugger (or to run the first kdb command after the panic). As it happens the timeout value is already an exported kernel symbol so all the info is there for us to use.Doing so would save us imposing further configuration burden on the user" > > Would it be cleaner/clearer to add some new standalone control for > this? One which is only present if CONFIG_KGDB. Original Android patch uses separate configuration but since we can achieve the same with already existing kernel symbol,we have used panic_timeout. > > > We appear to have forgotten to document panic_timeout. Sigh. Regards, Kiran -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/