How could I allocate a huge memory in rtdm driver?

孙世龙 sunshilong369 at
Mon Apr 13 10:47:26 CEST 2020


     Thanks a lot for your reply.

     I am not a native speaker. I hope you won't be confused by my poor

    The huge memory allocated is no need to be contiguous.    I have seen
the suggestion that cma is not recommend to be used with xenomai through
Philippe Gerum have allready relaxed the requirement on CONFIG_MIGRATION to
support cma. You could see the commit which commit id is 265ca3c3c for
detail .

    The memory will be used to store high definition video to be processed
later .Though many image processing algorithms require contiguous memory, I
do not need contiguous memory indeed.

  Best regards.

Richard Weinberger <richard.weinberger at> 于2020年4月13日周一 下午4:17写道:

> On Mon, Apr 13, 2020 at 9:21 AM 孙世龙 via Xenomai <xenomai at>
> wrote:
> >
> > Hi,
> >      I am using xenomai 3.1.
> >
> >      How could I allocate a huge memory which may be larger then 50MB in
> > rtdm driver?
> >
> >      I have tried rtdm_malloc function,but it returns NULL.
> Depends on the use case, what exactly do you need?
> Physical contiguous memory? Who should use it?
> But 50MiB is a lot, in any context.
> I'd allocate it in a non-realtime context with either vmalloc(), cma
> or requesting
> pages manually and then provide the allocated memory to my RT related code.
> --
> Thanks,
> //richard

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