[libdispatch-dev] GCD libdispatch w/Blocks support working
on Free (f
Steve Kargl
sgk at troutmask.apl.washington.edu
Tue Oct 6 20:35:18 UTC 2009
On Tue, Oct 06, 2009 at 09:29:50PM +0100, Robert N. M. Watson wrote:
>
> On 6 Oct 2009, at 19:50, Chuck Swiger wrote:
>
> >Hi, Hans--
> >
> >On Oct 2, 2009, at 5:40 AM, Hans Petter Selasky wrote:
> >>Can the Apple's "Blocks" C language extension be used when
> >>programming in the kernel? Or is this a user-space only feature?
> >
> >While the main benefit of blocks is in conjunction with libdispatch
> >for userland apps, they can be used by themselves, in the kernel or
> >elsewhere.
>
> When a block is instantiated (perhaps not the formal terminology), the
> blocks runtime allocates memory to hold copies of relevant variables
> from the calling scope. This memory allocation may present an issue in
> some calling contexts in the kernel -- in particular, it won't be
> appropriate in contexts were non-sleepable locks are held, interrupt
> threads, etc. While it should be possible to use the primitive in the
> kernel, we may want to think carefully about these implications. Also,
> blocks are currently specific to clang, although with any luck gcc
> will grow them also.
>
It is unlikely that gcc will grow support for block any time soon.
http://gcc.gnu.org/ml/gcc/2009-09/msg00272.html
--
Steve
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