On 30-12-07 21:46, Ingo Molnar wrote:
* Alan Cox <[email protected]> wrote:
So the current plan is to go with an io_delay=udelay default in v2.6.25,
to give this a migration window, and io_delay=none in v2.6.26 [and a
complete removal of arch/x86/kernel/io_delay.c], once the _p() uses are
fixed up. This is gradual enough to notice any regressions we care about
and also makes it nicely bisectable and gradual.
You will break systems if you blindly go around disabling _p delays
for ISA and LPC bus devices. The DEC Hinote laptops for example are
well known for requiring the correct ISA and other keyboard controller
delays. I don't expect anyone to test with a hinote or see it until it
hits Debian or similar 'low resource' friendly devices.
well, using io_delay=udelay is not 'blindly disabling'.
On the other hand, the patch you just posted that makes io_delay=none the
default _is_ blindly disabling. So that wasn't for consumption?
io_delay=udelay additionally blindly disables the race-hiding effect the
outb has on SMP and that Alan is seeing so many of. Should also wait for
more driver review.
Rene.
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