Intel I350 mini-PCIe card (igb) on Mirabox (mvebu / Armada 370)

[Willy Tarreau]

Hi Jason,

On Tue, Apr 08, 2014 at 01:21:41PM -0600, Jason Gunthorpe wrote:
> On Tue, Apr 08, 2014 at 09:15:14PM +0200, Willy Tarreau wrote:
> 
> > OK that's what I understood, but I mean why rounding down instead of up
> > in order to correctly cover the window the device expects ? And we all
> > found that rounding up fixed our respective devices (3 igb NICs, one
> > myri10ge NIC, one SATA controller I believe).
> > 
> > By rounding up you'd have had 1ffffff instead, which at least covers the
> > window the device expects.
> 
> It is also an error to configure the mbus to have overlaping windows
> and the code checks for overlaps with the base/size given. If we round
> up then it might create an overlap.

OK, Thomas just explained this to me over the phone, it makes sense now.
In fact, I think that a mix between your patch to create multiple windows
and something Thomas wanted to do (ie allocate larger and inform the PCI
core) would be a good solution by preferring to round up small windows
(low waste) and create multiple windows where the waste is too large
(eg: address space divided by the max number of windows).

Thank you for your explanation.

Willy