Re: [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use

Le 12/07/2019 à 14:22, Michael Ellerman a écrit :

Christophe Leroy [off-list ref] writes:

quoted

Le 12/07/2019 à 08:25, Michael Ellerman a écrit :

quoted

"Aneesh Kumar K.V" [off-list ref] writes:

...

quoted

quoted

quoted

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 11caa0291254..b181d6860f28 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c

@@ -250,15 +250,22 @@ static void oops_end(unsigned long flags, struct pt_regs *regs,
   }
   NOKPROBE_SYMBOL(oops_end);
   
+static char *get_mmu_str(void)
+{
+	if (early_radix_enabled())
+		return " MMU=Radix";
+	if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
+		return " MMU=Hash";
+	return "";
+}

We don't change MMU once we're up, so just do this logic once and stash
it into a static string, rather than rechecking on every oops.

Do we really have oops so often that we have to worry about that ?

Sometimes :)

But no I don't mean it's a performance issue, it just seems simpler to
compute the value once and store it. In fact for most platforms it can
just be a static string at compile time, it's only 64-bit Book3S that
needs to do anything at runtime.

Right, but I'm sure GCC will take care of that since the function is 
static and called only once.

Christophe

cheers