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I think that it's better to detect DMA misuse at build time rather than calling BUG_ON. Architectures that can't do DMA need to define CONFIG_NO_DMA. Thanks to Sam Ravnborg for explaining how CONFIG_NO_DMA and CONFIG_HAS_DMA work: http://marc.info/?l=linux-kernel&m=128359913825550&w=2 HAS_DMA is defined like this: config HAS_DMA boolean depends on !NO_DMA default y So to set HAS_DMA to true an arch should do: 1) Do not define NO_DMA 2) Define NO_DMA abd set it to 'n' Must archs - including um - used principle 1). In the um case we want to say that we do NOT have any DMA. This can be done in two ways. a) define NO_DMA and set it to 'y' b) redefine HAS_DMA and set it to 'n'. The patch you provided used principle b) where other archs use principle a). So I suggest you should use principle a) for um too. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Jeff Dike <jdike@addtoit.com> Cc: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| .. | ||
| a.out-core.h | ||
| apic.h | ||
| arch_hweight.h | ||
| asm-offsets.h | ||
| auxvec.h | ||
| bugs.h | ||
| cache.h | ||
| checksum.h | ||
| common.lds.S | ||
| cputime.h | ||
| current.h | ||
| delay.h | ||
| desc.h | ||
| device.h | ||
| dma.h | ||
| emergency-restart.h | ||
| fixmap.h | ||
| ftrace.h | ||
| futex.h | ||
| hardirq.h | ||
| hw_irq.h | ||
| io.h | ||
| irq_regs.h | ||
| irq_vectors.h | ||
| irq.h | ||
| irqflags.h | ||
| kdebug.h | ||
| kmap_types.h | ||
| mmu_context.h | ||
| mmu.h | ||
| mutex.h | ||
| page_offset.h | ||
| page.h | ||
| param.h | ||
| pci.h | ||
| pda.h | ||
| pgalloc.h | ||
| pgtable-2level.h | ||
| pgtable-3level.h | ||
| pgtable.h | ||
| processor-generic.h | ||
| ptrace-generic.h | ||
| required-features.h | ||
| sections.h | ||
| segment.h | ||
| setup.h | ||
| smp.h | ||
| system.h | ||
| thread_info.h | ||
| timex.h | ||
| tlb.h | ||
| tlbflush.h | ||
| topology.h | ||
| uaccess.h | ||
| xor.h | ||