On Mon, Apr 28, 2014 at 11:40:36PM +0200, Borislav Petkov wrote: > On Mon, Apr 28, 2014 at 02:50:29PM -0600, Bjorn Helgaas wrote: > > This I/O ECS thing seems likely to cause future problems. My > > understanding (based on sec 2.8 of [1]) is that enable_pci_io_ecs() > > and pci_enable_pci_io_ecs() are there to enable access to extended > > config space (offsets 256-4095) via the 0xcf8/0xcfc I/O ports. > > > > Per sec 4.1.1 of [2], we should be using ECAM (the memory-mapped > > enhanced configuration mechanism, i.e., MMCONFIG) to access extended > > config space, and the BIOS should supply an MCFG table. > > > > So why do we need to enable I/O access to ECS on AMD chips at all? Is > > this a workaround for a broken BIOS that doesn't supply an MCFG table? > > That's a good question. 831d991821dae doesn't say but I have a hunch > Andreas and/or Robert should know. I seem to vaguely remember it > might've been because of a missing MCFG but have flushed it out of the > cache long time ago. > > Let's ask them. > > Andreas, Robert, guys, do you remember why we did the PCI IO ECS access? > B0rked BIOSes? I am sure, it's because some server systems had MMIO ECS access not enabled in BIOS. I can't remember which systems were affected. Andreas -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
