Message ID | 5673D683.8050002@arm.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
On Fri, Dec 18, 2015 at 09:48:51AM +0000, Marc Zyngier wrote: > On 18/12/15 09:34, Russell King - ARM Linux wrote: > > On Fri, Dec 18, 2015 at 09:16:13AM +0000, Marc Zyngier wrote: > >> Having IPI_CPU_BACKTRACE as SGI15 may not work if the kernel is > >> running in non-secure mode and that the secure firmware has > >> decided to follow ARM's recommendations that SGI8-15 should > >> be reserved for secure purpose. > >> > >> Now that we are "only" using SGI0-6, change IPI_CPU_BACKTRACE > >> to use SGI7, which makes it more likely to work. > > > > We should add a comment to the enum explaining this, so it's obvious > > for the future - best place is after the IPI_CPU_BACKTRACE entry. > > Not everyone checks the git logs for these kinds of details. > > Indeed. How about something like this: Yep.
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index fe517f1..37312f6 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -73,6 +73,11 @@ enum ipi_msg_type { IPI_IRQ_WORK, IPI_COMPLETION, IPI_CPU_BACKTRACE, + /* + * SGI8-15 can be reserved by secure firmware, and thus may + * not be usable by the kernel. Please keep the above limited + * to at most 8 entries. + */ }; static DECLARE_COMPLETION(cpu_running);