Re: Resource assignment oddities

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On Thu, May 23, 2013 at 11:17 AM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> On Thu, May 23, 2013 at 10:12 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
>> On Thu, May 23, 2013 at 11:08 AM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
>>>
>>> Good, will resend this as complete form to Bjorn for v3.10.
>>
>> I haven't seen anything this actually fixes yet, except that maybe it
>> removes some "can't assign" messages.  That doesn't sound like v3.10
>> material.
>
> io port "can't assign" still there.

The "can't assign io" message is harmless.  The host bridge doesn't
support I/O port space, so we'll *never* be able to assign IO space.
The best we can do for this part of the problem is to get rid of the
message, and that's not urgent for v3.10.  Actually, I don't think we
*should* get rid of the message; if we can't assign IO space to an IO
BAR, I want to know about it.  Maybe the message should be clearer or
less alarming, but it should be there.

> the problem that it fixed: don't fallback wrongly for mmio when ioport
> fails with must+optional.
>
> because if it fall back to mmio must-only, later extending to cover
> optional will
> not find extra space as mmio range and mmio-pref range in the bridge
> is connected
> together.

I know that we retry when we don't need to.  If the retry results in
MEM assignments that are *worse* than the original ones, that might be
a problem we should fix.  But that problem should have nothing to do
with I/O port space.  Conceptually, if we retry because IO assignment
failed, the MEM assignments should not change.

I could probably grope through your logs and figure out whether this
is happening, but it's your job to do that legwork and convince me
that a change is necessary.

Bjorn
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