Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops

Alan Cox
2007-12-10T12:08:59Z

> Really?
>
> udelay() seems to use
> ... cpu_data(raw_smp_processor_id()).loops_per_jiffy ..

Ok that should be a good safety
>
> ..so it seems that bug trap is already there... because
> raw_smp_processor_id() will probably just oops...

And I double checked my docs - they say 8 cycles - 1uS

Incidentally some of the drivers seem buggy for SMP. The bus locking
nature of the inb_p probably hid this but they don't all seem to have
sufficient locking to ensure that we don't get back to back cycles
without delays

Alan