On Fri, Apr 8, 2022 at 4:21 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > On Fri, Apr 08, 2022 at 04:17:16PM +0200, Arnd Bergmann wrote: > > On Fri, Apr 8, 2022 at 3:32 PM Daniel Thompson > > <daniel.thompson@xxxxxxxxxx> wrote: > > > On Thu, Mar 31, 2022 at 05:44:55PM +0200, Arnd Bergmann wrote: > > > > > > There is some prior art for this sort of feature. AFAICT SGI UV has a > > > similar mechanism that can send an NMI-with-no-side-channel to the > > > kernel. The corresponding driver offers a range of actions using a > > > module parameter: > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/platform/uv/uv_nmi.c#n180 > > > > > > I don't think a hardcoded 'c' makes any sense. With a hardcoded argument > > > it is just obfuscation. However it is certainly seems attractive to be > > > able to reuse handle_sysrq() to provide a more powerful set of actions. > > > > How about a module parameter that allows picking a sysrq character then? > > Module parameters are so 1990, as this is a platform device, why not get > it from DT? This machine doesn't use DT. I suppose the same could be done with an EFI variable, but with a module parameter you get the added benefit of having both a boot time kernel command line argument, and the option to override it at run time. Arnd
