Messages in this thread Patch in this message |  | | Date | Fri, 25 Aug 2017 08:45:40 +0200 | From | Michal Hocko <> | Subject | Re: arch/arm/kernel/setup.c fails to compile for NOMMU |
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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? --- From 2707f3bf00181bbc9dcf6a1f287eb7369141e955 Mon Sep 17 00:00:00 2001 From: Michal Hocko <mhocko@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 <mhocko@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
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