Large shared memory segment in kernel

Large shared memory segment in kernel

[Stephane Letz]

We would like to allocate a large memory segment (several Mb) in a kernel
module so that to access the memory in the kernel module and in user space
application. (be implementing the mmap function in the kernel module)
Is is something that could be done ?  Or kernel modules should only mmap
small amount of memory?

Thanks

Stephane Letz


Grame: Centre National de creation musicale
9, Rue du Garet
69001 Lyon
Tel: 04-72-07-37-00
Fax: 04-72-07-37-01
Web: www.grame.fr


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Re: Large shared memory segment in kernel

[Stephen C. Tweedie]

Hi,

On Wed, May 24, 2000 at 01:14:40PM +0200, Stephane Letz wrote:

> We would like to allocate a large memory segment (several Mb) in a kernel
> module so that to access the memory in the kernel module and in user space
> application. (be implementing the mmap function in the kernel module)
> Is is something that could be done ?  Or kernel modules should only mmap
> small amount of memory?

As long as you are happy for the memory to be non-contiguous, then
it should be fine.  If you are using 2.3 kernels, the kiobuf code at

    ftp.uk.linux.org:/pub/linux/sct/fs/raw-io/kiobuf.2.3.99.pre9-2.tar.gz

has a set of helper functions which make it trivial to do this from 
device drivers (and the patch includes a sample driver to show exactly
how it works).

--Stephen
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