mmap implementation for cdev
jhb at freebsd.org
Fri Dec 9 15:48:29 UTC 2011
On Saturday, December 03, 2011 5:37:01 am Filippo Sironi wrote:
> I need to access the memory both from user space and kernel space, I cannot
do that (simply) with an mmap or thread-specific storage if I recall
You could allocate a dedicated VM object for each thread's information and
populate it with a single page. You could then return that from a
csw->d_mmap_single() routine. You could also use some routines I'm about to
add for the shm_open() API that let you easily map shm_open() objects into the
kernel where threads create a shm object in userland and pass the fd into the
kernel to let the kernel map it.
> On 03/dic/2011, at 11.00, Poul-Henning Kamp wrote:
> > In message <A842C229-1846-408A-999A-9347770EFE7A at gmail.com>, Filippo
> > tes:
> > Why don't you just use mmap(2) ? I couldn't see anything you
> > couldn't do with it.
> > There's also support in pthread for thread specific storage, which
> > should be your first choice.
> > --
> > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
> > phk at FreeBSD.ORG | TCP/IP since RFC 956
> > FreeBSD committer | BSD since 4.3-tahoe
> > Never attribute to malice what can adequately be explained by
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