On Sat, Jun 16, 2012 at 2:48 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: >> >> We'd better to make all path share as most code as possible. >> 1. hostbridge scanning during boot -- early, it will check chipset and e820 >> 2. MCFG checking during boot -- early, it will check e820 >> 3. MCFG checking during boot -- late, it will check acpi pnp >> 4. _CBA checking for hotplug-able pci root bus but it is installed during boot. >> 5. _CBA checking for hotplug-able pci root bus during run time. >> >> please keep mapping for all entries in MCFG table. aka 1, 2, 3. >> I have some local patches that will read ext pci conf space before scan pci bus. >> please check attached one for nehalem-ioh. > > I don't think it's a requirement that Gerry keep your Nehalem patch > working. Your intel_bus.c is not in the tree and you haven't provided > an explanation for why it should be. > > The only requirement I'm aware of for PCI config access before we > discover the host bridges via ACPI is for segment group 0, bus 0, as > mentioned in ACPI spec 5.0, sec 5.2.3.1, PDF page 143, and I think > that applies only to the first 0x100 bytes of config space. I don't > think there's a requirement for access to the extended configuration > space (bytes 0x100-0xFFF). I do not see a requirement that this > pre-host bridge access happen via MMCONFIG; as far as I can tell, we > can use the legacy 0xCF8/0xCFC mechanism. that one shot for intel host bridge resource discovery before root bus scanning, will need to access registers above 0x100. Current MCFG handling have some sanitary checking during probing. Now Jiang is trying to free result and cache it for two MCFG path 2/3. and later use cached and map again for entries from cached entries. but when use those cached entries sanitary of those entries are lost. so choice would be 1. cache all checked MMCFG result and use that later 2. or just leave current MCFG handling alone, just add _CBA support. like Jiang -v4 version. Thanks Yinghai -- 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
