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authorFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>2010-10-26 17:22:18 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-26 19:52:12 -0400
commitd911202e3f722c29065942400ea108b7096bdac7 (patch)
tree17c0a4c8d2fa36db4469ddb21e7edee29184df74 /arch/um/Kconfig.um
parent98c532ecbe582586e204688c6cde7e27580cc43f (diff)
uml: define CONFIG_NO_DMA
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>
Diffstat (limited to 'arch/um/Kconfig.um')
-rw-r--r--arch/um/Kconfig.um3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/um/Kconfig.um b/arch/um/Kconfig.um
index ec2b8da1aba4..ffe0934a3ccf 100644
--- a/arch/um/Kconfig.um
+++ b/arch/um/Kconfig.um
@@ -147,3 +147,6 @@ config KERNEL_STACK_ORDER
147 This option determines the size of UML kernel stacks. They will 147 This option determines the size of UML kernel stacks. They will
148 be 1 << order pages. The default is OK unless you're running Valgrind 148 be 1 << order pages. The default is OK unless you're running Valgrind
149 on UML, in which case, set this to 3. 149 on UML, in which case, set this to 3.
150
151config NO_DMA
152 def_bool y