Messages in this thread | | | Date | Tue, 15 Jul 2008 10:24:05 -0400 | From | "Mike Frysinger" <> | Subject | Re: linux-next: 1ea0704e (ptep_modify_prot transaction abstraction) breaks no-mmu |
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On Thu, Jul 3, 2008 at 11:53 AM, Jeremy Fitzhardinge wrote: > Mike Frysinger wrote: >> the functions added to asm-generic/pgtable.h are only used by >> mm/mprotect.c (a MMU-only file), but they were not added inside of the >> CONFIG_MMU ifdef block. since the functions rely on things inside of >> CONFIG_MMU (the lines just above in pgtable.h), we get build failure >> on all no-mmu setups: >> CC init/main.o >> In file included from include/asm/pgtable.h:94, >> from include/linux/mm.h:39, >> from include/asm/dma.h:39, >> from include/linux/bootmem.h:8, >> from init/main.c:27: >> include/asm-generic/pgtable.h: In function '__ptep_modify_prot_start': >> include/asm-generic/pgtable.h:210: error: implicit declaration of >> function 'ptep_get_and_clear' >> include/asm-generic/pgtable.h:210: error: incompatible types in return >> make[1]: *** [init/main.o] Error 1 >> make: *** [init/main.o] Error 2 > > Uh, OK. What does mprotect do on a nommu system?
it depends on the port. by default, i'm pretty sure mprotect on all nommu systems are realistically pretty much noops. the Blackfin can do real protection (CONFIG_MPU), but with significant performance degradation (since the page fault handler is not in hardware nor hardware assisted in any way).
> Would it be sufficient to > move the definitions of __ptep_modify_prot_start/commit out of a CONFIG_MMU > block, or provide separate no-op versions?
simply move them into CONFIG_MMU for now -mike
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