> On 4 Aug 2017, at 7:38 PM, James Morse <james.mo...@arm.com> wrote: > > Hi Hoeun, > >> On 04/08/17 08:02, Hoeun Ryu wrote: >> Commit 0ee5941 : (x86/panic: replace smp_send_stop() with kdump friendly >> version in panic path) introduced crash_smp_send_stop() which is a weak >> function and can be overriden by architecture codes to fix the side effect >> caused by commit f06e515 : (kernel/panic.c: add "crash_kexec_post_ >> notifiers" option). > > If I've understood correctly: if we boot with this option core code doesn't > use > our machine_crash_shutdown(), and instead calls crash_smp_send_stop(), which > we > don't have, so it uses the default smp_send_stop(), which doesn't save the > regs. > > Thanks for catching this! > > > Could we rename smp_send_crash_stop() crash_smp_send_stop() and add the > called-twice logic there? They are similar enough that I'm getting them > muddled > already!
I think it is possible, I will reflect it in v2. Thank you for the review. > > Thanks, > > James > > >> ARM64 architecture uses the weak version function and the problem is that >> the weak function simply calls smp_send_stop() which makes other CPUs >> offline and takes away the chance to save crash information for nonpanic >> CPUs in machine_crash_shutdown() when crash_kexec_post_notifiers kernel >> option is enabled. >> >> Calling smp_send_crash_stop() in the function is useless because all >> nonpanic CPUs are already offline by smp_send_stop() in this case and >> smp_send_crash_stop() only works against online CPUs. >> >> The result is that /proc/vmcore is not available with the error messages; >> "Warning: Zero PT_NOTE entries found", "Kdump: vmcore not initialized". >> >> crash_smp_send_stop() is implemented for ARM64 architecture to fix this >> problem and the function (strong symbol version) saves crash information >> for nonpanic CPUs using smp_send_crash_stop() and machine_crash_shutdown() >> tries to save crash information for nonpanic CPUs only when >> crash_kexec_post_notifiers kernel option is disabled. > >