Hi Michal, On 06.04.2018 11:56, Michal Hocko wrote: > On Fri 25-08-17 08:45:40, Michal Hocko wrote: >> On Thu 24-08-17 17:17:41, Russell King - ARM Linux wrote: >> > On Fri, Aug 18, 2017 at 01:24:02PM +0200, Michal Hocko wrote: >> > > Hi Russel, >> > > I have a battery of configs for compile testing and for some time I've >> > > been seeing the following compilation error with nommu config (attached) >> > > >> > > arch/arm/kernel/setup.c: In function 'reserve_crashkernel': >> > > arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first >> > > use in this function) >> > > crash_size, SECTION_SIZE); >> > > >> > > I didn't get to look what is going on here, maybe my config is just too >> > > artificial but the primary reason is that SECTION_SIZE is not defined in >> > > pgtable-nommu.h. To be honest I am not familiar with nommu very much and >> > > it smells like the whole reserve_crashkernel doesn't really make any >> > > sense on those configs. Could you have a look what is the best fix >> > > please? >> > >> > Hi, >> > >> > I suspect that mach-netx has never been tested in nommu configurations >> > (ditto for many of the older platforms, which pre-date merging nommu >> > support.) >> > >> > Maybe the best solution is to make these old platforms depend on MMU. >> > >> > However, I'm wondering whether kexec makes sense for !MMU - that's >> > probably something that hasn't been tested and doesn't actually work. >> > So maybe another approach would be to make kexec depend on MMU for >> > ARM - but I'm afraid I don't really know. >> >> Yeah, I've disabled KEXEC in my testing config. All I do care about is >> to test nommu specific code paths in MM code. >> >> > I only have very limited nommu experience. >> >> me too >> >> So what would you say about the following? > > It's been some time and it seems this has fallen between cracks. Is this > worth puruing or I should just forget about it and drop it on the floor?
I actually came across this issue during some randconfig testing. Your change looks good to me: Reviewed-by: Stefan Agner <ste...@agner.ch> Fixes for the ARM core usually go through Russell's patch tracker, did you submit you patch there? See also: https://www.arm.linux.org.uk/developer/patches/info.php -- Stefan >> --- >> From 2707f3bf00181bbc9dcf6a1f287eb7369141e955 Mon Sep 17 00:00:00 2001 >> From: Michal Hocko <mho...@suse.com> >> Date: Fri, 25 Aug 2017 08:40:09 +0200 >> Subject: [PATCH] arm: make kexec depend on MMU >> >> arm nommu config with KEXEC enabled doesn't compile >> arch/arm/kernel/setup.c: In function 'reserve_crashkernel': >> arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first >> use in this function) >> crash_size, SECTION_SIZE); >> >> since 61603016e212 ("ARM: kexec: fix crashkernel= handling") which is >> over one year without anybody noticing. I have only noticed beause of >> my testing nommu config which somehow gained CONFIG_KEXEC without >> an intention. This suggests that nobody is actually using KEXEC >> on nommu ARM configs. It is even a question whether kexec works with >> nommu. >> >> Make KEXEC depend on MMU to make this clear. If somebody wants to enable >> there will be probably more things to take care. >> >> Signed-off-by: Michal Hocko <mho...@suse.com> >> --- >> arch/arm/Kconfig | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig >> index 3f4aa9179337..c8603195d7fc 100644 >> --- a/arch/arm/Kconfig >> +++ b/arch/arm/Kconfig >> @@ -2003,6 +2003,7 @@ config KEXEC >> bool "Kexec system call (EXPERIMENTAL)" >> depends on (!SMP || PM_SLEEP_SMP) >> depends on !CPU_V7M >> + depends on MMU >> select KEXEC_CORE >> help >> kexec is a system call that implements the ability to shutdown your >> -- >> 2.13.2 >> >> -- >> Michal Hocko >> SUSE Labs
