On Tue, Nov 18, 2003 at 02:02:28PM +1100, Benjamin Herrenschmidt wrote:

On Tue, 2003-11-18 at 12:16, Juergen Kienhoefer wrote:

quoted

Guys,
Look at the folloging test program. It mmaps memory, puts some
instructions in it and executes it.
Sometimes it works, sometimes it crashes with illegal instruction.
This smells like cache problems.
Should the kernel clean the instruction cache for these addresses
in mmap system call?
Thanks for any thoughts!
Juergen

It's your duty to ensure cache coherency. Actually, the kernel
will eventually clean the icache for newly mapped in blank pages,

If you mean zeroed pages for blanked, I believe that it is wrong.
The reason being that 0 is an invalid instruction so that the code
would trap in any case.

Maybe I'm wrong, but I seem to remember this as an optimization
that Paulus implemented some time ago.

	Gabriel

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