Re: [PATCH v3] MM: CMA: add a simple kernel module as the helper totest CMA

[Michal Nazarewicz]

> On 03/07/2012 11:14 AM, Barry Song wrote:
> > Any write request to /dev/cma_test will let the module to allocate memory from
> > CMA, for example:
> >
> > 1st time
> > $ echo 1024>  /dev/cma_test
> > will require cma_test to request 1MB(1024KB)
> > 2nd time
> > $ echo 2048>  /dev/cma_test
> > will require cma_test to request 2MB(2048KB)
> >
> > Any read request to /dev/cma_test will let the module to free the 1st valid
> > memory from CMA, for example:
> >
> > 1st time
> > $ cat /dev/cma_test
> > will require cma_test to free the 1MB allocated in the first write request
> > 2nd time
> > $ cat /dev/cma_test
> > will require cma_test to free the 2MB allocated in the second write request

On Wed, 07 Mar 2012 05:14:36 +0100, Cong Wang <xiyou.wangcong@xxxxxxxxx> wrote:
> Any reason why using /dev not /proc or /sys?

Because /proc is for processes and /sys is for stable, documented APIs.

If anything, debugfs might make some sense, but since the module needs struct
device anyway, it can just register a misc device, which is simpler and does
not require debugfs to be compiled.

--
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