Messages in this thread | | | Date | Mon, 11 Mar 2019 09:52:08 +0100 | From | Michal Hocko <> | Subject | Re: arch/arm/kernel/setup.c fails to compile for NOMMU |
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On Tue 05-03-19 23:08:45, Stefan Agner wrote: > 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 <stefan@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
Thanks! I am quite busy though so please feel free to resubmit if you feel this is worth it.
> -- > Stefan > > >> --- > >> 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
-- Michal Hocko SUSE Labs
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