Messages in this thread | | | Date | Thu, 25 Feb 2010 11:28:08 +0900 | From | Tejun Heo <> | Subject | Re: [PATCH 2.6.34] ehci-hcd: add option to enable 64-bit DMA support |
| |
Hello,
On 02/24/2010 09:26 AM, Robert Hancock wrote: > The fact that Windows 7 is now using the feature also means that there > aren't likely to be too many machines where the 64-bit addressing is > reported but doesn't work. Which means that aside from the NVIDIA > quirk, I think enabling 64-bit addressing should be relatively safe.
(following thread from the ATA side) I'm with Greg on this. USB2.0 is quite slow on today's standard and most 64bit machines now have IOMMU of some kind anyway. If we have problems on IOMMU (sw or hw) allocation, I think it should be fixed there.
64bit support even in libata was quite painful with quirky BIOSen, PCI host controllers, bridges and the controllers themselves. ATA being a major secondary storage subsystem, libata had to do it but even then for many those enabling trials, I think we've lost more than we gained. There just isn't much point in trying to enable a shiny new feature on an aging platform or technology. The gain might be there but the downside is we end up catching fallout cases where boot fails or data corrupts after many months later if we're very lucky. It's just not worth it.
Thanks.
-- tejun
| |