+ Robin and Christoph On 16/10/17 06:27, Marian Mihailescu wrote: > I am using 4.14-rc4 with a patch on top that includes > arch/arm/include/asm/dma-mapping.h in a module. > > I have MMU enabled, so > select DMA_NOOP_OPS if !MMU > does nothing for me, and I get a compile error because dma_noop_ops is > unknown.
Can you post an error message here, please? > > Maybe I should include linux/dma-mapping.h? Where to include? In your driver or what? > > Thanks for the quick reply. with CONFIG_MMU compiler should optimise out dma_noop_ops in: return IS_ENABLED(CONFIG_MMU) ? &arm_dma_ops : &dma_noop_ops; What toolchain are you using? Cheers Vladimir > > > On Mon, Oct 16, 2017 at 2:28 PM, Randy Dunlap <[email protected]> wrote: >> On 10/15/17 20:29, Randy Dunlap wrote: >>> On 10/15/17 20:27, Randy Dunlap wrote: >>>> On 10/15/17 19:27, Marian Mihailescu wrote: >>>>> After commit 7844572c633964c864d9f32dc3f2a8ffe5d70371, dma_noop_ops >>>>> are built only for architectures that use it. >>>>> >>>>> For ARM architecture, CONFIG_DMA_NOOP_OPS is not selected, and cannot >>>>> be selected. >> >> What kernel version are you looking at? >> I see that it is selected: >> >> --- a/arch/arm/Kconfig >> +++ b/arch/arm/Kconfig >> @@ -22,6 +22,7 @@ config ARM >> select CLONE_BACKWARDS >> select CPU_PM if (SUSPEND || CPU_IDLE) >> select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS >> + select DMA_NOOP_OPS if !MMU >> select EDAC_SUPPORT >> select EDAC_ATOMIC_SCRUB >> select GENERIC_ALLOCATOR >> >> >> That's in commit ID 1c51c429f30ea10428337f3a33c12059ba59f668 from May 24, >> 2017. >> >>>>> However, arch/arm/include/asm/dma-mapping.h is referencing dma_noop_ops: >>>>> >>>>> static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type >>>>> *bus) >>>>> { >>>>> return IS_ENABLED(CONFIG_MMU) ? &arm_dma_ops : &dma_noop_ops; >>>>> } >>>>> >>>>> I will let a maintainer suggest the best resolution for this :) >>>>> >>>> >>>> add Bart and iommu mailing list. >>>> >>> >>> and add Vladimir. >>> >>> >> >> >> -- >> ~Randy
