From d911202e3f722c29065942400ea108b7096bdac7 Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Tue, 26 Oct 2010 14:22:18 -0700 Subject: 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 Cc: Miklos Szeredi Cc: Jeff Dike Cc: Sam Ravnborg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/Kconfig.um | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/um/Kconfig.um') 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 This option determines the size of UML kernel stacks. They will be 1 << order pages. The default is OK unless you're running Valgrind on UML, in which case, set this to 3. + +config NO_DMA + def_bool y -- cgit v1.2.1