Hi Adrian, Am 30.09.2024 um 21:38 schrieb John Paul Adrian Glaubitz:
Hello Jean-Michel, On Mon, 2024-09-30 at 10:19 +0200, Jean-Michel Hautbois wrote:I wanted to try PREEMPT_RT. I added the support for it: diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig index c7880f375518..b0360167574d 100644 --- a/arch/m68k/Kconfig +++ b/arch/m68k/Kconfig @@ -39,6 +39,7 @@ config M68K select OLD_SIGSUSPEND3 select UACCESS_MEMCPY if !MMU select ZONE_DMA + select ARCH_SUPPORTS_RT config CPU_BIG_ENDIAN def_bool y And set PREEMPT_RT then it fails to boot: [ 6.517000] BUG: scheduling while atomic: init/1/0x00010001 (...) Any idea, thoughts :-) ?From what I know an architecture has to be explicitly ported to support a realtime kernel. Simply enabling the feature therefore won't work.
Making sure softirqs are run from a separate kernel thread and not from atomic context would be a good start. Adding preempt_disable() / preempt_enable() around more critcal sections may be needed as well.
Git history of those architectures that support PREEMPT_RT might be informative.
Cheers, Michael
Adrian
