On Wed, 2008-06-25 at 18:00 -0700, Zhao Yakui wrote: > On Wed, 2008-06-25 at 09:57 -0700, Alok Kataria wrote: > > On Wed, 2008-06-25 at 01:38 -0700, Zhao Yakui wrote: > > > On Tue, 2008-06-24 at 23:04 -0700, Alok kataria wrote: > > > The pci_mem_start is still gotten by parsing the E820 table.But the > > > input parameter start_addr will be used in the function of > > > e820_search_gap. > > > If the following is the resource start address returned by the PCI0 > > > _CRS object , maybe the different pci_mem_start will be gotten. > > > 0xE0000000 > > > 0xE4000000 > > > > > > At the same time if several start address is returned by the _CRS > > > object, the e820 table will be parsed several times. > > > > Yes we will parse e820 several times, but we don't initialize > > pci_mem_start in every pass. > > It will be initialized only twice once via the e820_setup_gap code path > > and once via pci_setup_gap. > > And i think you agree that both of these are required ? > Agree with what you said and IMO it is OK. > > > > During the gap calculation the previous code or the code now in > > e820_setup_gap does this... > > calculates a gap in e820_map from 0 to 2^32. > > Initializes pci_mem_start. > > > > And now with this patch, the code in pci_setup_gap > > does this... > > for each _CRS under PCI0 > > search gap from start_addr of _CRS to 2^32 *[1]. > > Initialize pci_mem_start with the biggest gap that we could > > find. > Yes. But maybe the pci_mem_start obtained in pci_setup_gap will be > different with that obtained in e820_setup_gap on some bogus BIOS. > If the pci_mem_start obtained in pci_setup_gap can meet the requirement, > it is also reasonable. Ok, so the whole problem crops up from what if the BIOS itself is bogus. Ok in that case too we take proper care that pci_mem_start is within the expected limits, i.e. we make sure that 1. pci_mem_start is not initialized to an already allocated resource address and.. 2. pci_mem_start is within the lower 32bit of address space. I assume you also agree that all the checks are in place. Also it would be great if you could ACK both the patches as well. Thanks for the review. Alok > > Essentially, what we are doing is just limiting the gap calculation to a > > smaller address space depending on the ACPI information we get. > > > > Now then, what problem do you see with this approach ? > > *[1] > > While writing this mail i figured out that, instead of searching from > > start_addr of _CRS to 2^32 we should just search till *end_addr* of _CRS resource. > > I will send a patch to that effect. > If this, IMO it will be OK. > > Thanks, > > Alok > > > > > > > > > > Thanks. > > > Yakui > > > > > > > Thanks, > > > > Alok > > > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
