On Mon, Nov 22, 2010 at 03:31:24PM +0100, Per Fransson wrote: > On Mon, Nov 22, 2010 at 12:27 PM, Russell King - ARM Linux > <linux at arm.linux.org.uk> wrote: > > On Mon, Nov 22, 2010 at 10:47:40AM +0000, Russell King - ARM Linux wrote: > >> However, we do need smp_send_stop() to wait for a limited time for the > >> other CPUs to respond to the request. > > > > ARM: smp: make smp_send_stop() wait for secondary CPUs to stop > > > > Wait up to one second for secondary CPUs to respond to a request to > > stop. ?This avoids the sender CPU continuing and possibly destroying > > state before the recipients have had a chance to respond to the stop. > > However, if the recipients have crashed, we won't hang the sender > > CPU indefinitely. > > > > The point of the crash kernel functionality is to make it possible to grab a > snapshot of the system at the time of the crash. smp_send_stop() will > take the other cores offline, which makes the snapshot differ from the > crash state more than it has to. To be more concrete, any core dump > analysis tool which reads the cpu_online_mask to determine the number > of cpus in use will get an incorrect picture. Well, you can't go around randomly enabling interrupts to call functions that require interrupts to be enabled, so I guess it's not possible to save the state of the other cores. I guess you're going to have to come up with another solution.
