Re: [PATCH v2] powerpc/64s: introduce CONFIG_MAXSMP to test very large SMP

Excerpts from Michael Ellerman's message of November 23, 2021 11:01 am:

Michael Ellerman [off-list ref] writes:

quoted

Christophe Leroy [off-list ref] writes:

quoted

Le 09/11/2021 à 07:51, Nicholas Piggin a écrit :

...

quoted

quoted

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index a208997ade88..14c275e0ff93 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype

@@ -475,9 +475,14 @@ config SMP
  
  	  If you don't know what to do here, say N.
  
+# MAXSMP sets 8192 if COMPILE_TEST because that's what x86 has flushed out.
+# Exceeding that will cause a lot of compile errors. Have to deal with those
+# first.
  config NR_CPUS
-	int "Maximum number of CPUs (2-8192)" if SMP
-	range 2 8192 if SMP
+	int "Maximum number of CPUs (2-8192)" if SMP && !MAXSMP
+	range 2 16384 if SMP
+	default 16384 if MAXSMP && !COMPILE_TEST
+	default 8192 if MAXSMP && COMPILE_TEST

You can do less complex. First hit becomes the default, so you can do:

	default 8192 if MAXSMP && COMPILE_TEST
	default 16384 if MAXSMP

I did that when applying.

But I'll have to drop it, it breaks the allyesconfig build:

Ah, you still need patch 1/2 sorry I confused things by only re-sending 
this one.

https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20211105035042.1398309-1-npiggin@gmail.com/

Thanks,
Nick

  In file included from /home/michael/linux/arch/powerpc/include/asm/paravirt.h:15,
                   from /home/michael/linux/arch/powerpc/include/asm/qspinlock.h:6,
                   from /home/michael/linux/arch/powerpc/include/asm/spinlock.h:7,
                   from /home/michael/linux/include/linux/spinlock.h:93,
                   from /home/michael/linux/include/linux/mmzone.h:8,
                   from /home/michael/linux/include/linux/gfp.h:6,
                   from /home/michael/linux/include/linux/mm.h:10,
                   from /home/michael/linux/arch/powerpc/platforms/powernv/idle.c:9:
  /home/michael/linux/arch/powerpc/include/asm/cputhreads.h: In function ‘cpu_thread_mask_to_cores.constprop’:
  /home/michael/linux/arch/powerpc/include/asm/cputhreads.h:61:1: error: the frame size of 2064 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
     61 | }
        | ^
  /home/michael/linux/arch/powerpc/platforms/powernv/idle.c: In function ‘store_fastsleep_workaround_applyonce’:
  /home/michael/linux/arch/powerpc/platforms/powernv/idle.c:220:1: error: the frame size of 2080 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
    220 | }
        | ^
  cc1: all warnings being treated as errors
  make[4]: *** [/home/michael/linux/scripts/Makefile.build:287: arch/powerpc/platforms/powernv/idle.o] Error 1
  make[4]: *** Waiting for unfinished jobs....
  make[3]: *** [/home/michael/linux/scripts/Makefile.build:549: arch/powerpc/platforms/powernv] Error 2
  make[3]: *** Waiting for unfinished jobs....
  /home/michael/linux/arch/powerpc/kvm/book3s_hv_interrupts.S: Assembler messages:
  /home/michael/linux/arch/powerpc/kvm/book3s_hv_interrupts.S:66: Error: operand out of range (0x0000000000010440 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
  make[3]: *** [/home/michael/linux/scripts/Makefile.build:388: arch/powerpc/kvm/book3s_hv_interrupts.o] Error 1
  make[3]: *** Waiting for unfinished jobs....
  make[2]: *** [/home/michael/linux/scripts/Makefile.build:549: arch/powerpc/platforms] Error 2
  make[2]: *** Waiting for unfinished jobs....
  make[2]: *** [/home/michael/linux/scripts/Makefile.build:549: arch/powerpc/kvm] Error 2
  make[1]: *** [/home/michael/linux/Makefile:1846: arch/powerpc] Error 2
  make[1]: *** Waiting for unfinished jobs....
  make: *** [Makefile:219: __sub-make] Error 2

cheers