Dear Albert ARIBAUD,
Hi Marek,
On Wed, 10 Oct 2012 00:44:29 +0200, Marek Vasut marex@denx.de wrote:
Add memory barrier to cache invalidate and flush calls.
Memory barrier...
"You keep using that word. I do not think it means what you think it means." :)
A memory barrier's effect is only that all of the volatile accesses placed before it in the source code finish when the barrier executes, and that none of the volatile accesses placed after it in the source code starts before the barrier has executed.
Non-volatile accesses are not guaranteed to stay on one side of the barrier, and the barrier itself is not guaranteed to stay put during optimizations.
If what you intended was to ensure that e.g. all writes be finished when a flush occurs
Yes, that's pretty much it. To ensure that all writes to the flushed memory area are finished before the flushing happens.
or that no read happens before an invalide has executed, then adding memory clobbers is not an adequate solution.
What do you suggest?
If you were aiming for something else entirely, please don't hesitate to develop a description of the problem you wish to solve.
Amicalement,
Best regards, Marek Vasut