diff options
| author | FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> | 2010-10-26 14:22:18 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-26 16:52:12 -0700 |
| commit | d911202e3f722c29065942400ea108b7096bdac7 (patch) | |
| tree | 17c0a4c8d2fa36db4469ddb21e7edee29184df74 /arch/um/defconfig | |
| parent | 98c532ecbe582586e204688c6cde7e27580cc43f (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/defconfig')
| -rw-r--r-- | arch/um/defconfig | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/arch/um/defconfig b/arch/um/defconfig index 6bd456f96f9..564f3de65b4 100644 --- a/arch/um/defconfig +++ b/arch/um/defconfig @@ -566,7 +566,6 @@ CONFIG_CRC32=m # CONFIG_CRC7 is not set # CONFIG_LIBCRC32C is not set CONFIG_PLIST=y -CONFIG_HAS_DMA=y # # SCSI device support |