XIP aware file system

[Nicolas Pitre]

On Tue, 15 Feb 2005, David Woodhouse wrote:

> On Tue, 2005-02-15 at 11:38 -0500, Nicolas Pitre wrote:
> > Please study carefully xip_udelay() and try to understand _when_ it is 
> > OK to call other functions and when it is not.  This function is really 
> > where all the magic is happening.
> 
> Out of interest, how do we guarantee that there won't be speculative
> prefetching of icache? If you're relying on hardware-specific knowledge
> that it doesn't happen, please document that so that it doesn't bite
> people implementing the XIP primitives on other platforms.

See xip_enable().  You'll find:

	(void) map_read(map, adr);
	asm volatile (".rep 8; nop; .endr"); /* fill instruction prefetch */

Hopefully that should be suficient to avoid this problem.


Nicolas