[Q] comedi: vmap of the async->prealloc_buf
abbotti at mev.co.uk
Thu Dec 20 22:36:39 UTC 2012
On 20/12/12 17:09, H Hartley Sweeten wrote:
> Hello all,
> I have a question...
> In the comedi core, the asynchronous 'prealloc_buf' is vmap'ed after
> the page list has been allocated. The code in question looks like this:
> async->prealloc_buf =
> #ifdef PAGE_KERNEL_NOCACHE
> vmap(pages, n_pages, VM_MAP, PAGE_KERNEL_NOCACHE);
> vmap(pages, n_pages, VM_MAP, PAGE_KERNEL);
> Is the #ifdef something left over from an older kernel?
> Isn't PAGE_KERNEL_NOCACHE always defined?
Unfortunately not; it's arch dependent. Neither ARM nor PowerPC define
it, for example.
-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti at mev.co.uk> )=-
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