site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com Thread-index: Acor/9Tp6NiIP29IQt6yvUUJa2WJpgADHTDQ Thread-topic: IOBufferMemoryDescriptor::withOptions(kIOMemoryPhysicallyContiguous...) I think that's exactly what the problem is. I'm looking at Apple's USB audio driver, and they're using inTaskWithPhysicalMask(). A quick look at the IOBuffermemoryDescriptor code shows that withOptions() sets the mask to 0. Thanks, -Dan ________________________________________ From: Duane Murphy [duanemurphy@mac.com] Sent: Wednesday, September 02, 2009 12:01 PM To: Daniel Rice Cc: darwin-kernel@lists.apple.com Subject: Re: IOBufferMemoryDescriptor::withOptions(kIOMemoryPhysicallyContiguous...) -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 This sounds like the same problem I was having. The VM system in Snow Leopard seems much more capable of providing addresses outside of the 4GB range (ie 32b). I changed the code to use IOBufferMemoryDescriptor::inTaskWithPhysicalMask() in order to limit the requested memory range. I think the kIOMemoryPhysicallyContiguous option is still available with this interface. On Sep 2, 2009, at 11:05 AM, Daniel Rice wrote:

Some of our users are reporting a problem on 10.6. Basically, our usb device audio starts glitching after the computer has been running for a certain amount of time, and won't stop until they reboot the machine.

We saw a problem like this once before with the exact same symptoms under Leopard/Tiger. The cause ended up being that UHCI usb controllers require page aligned, physically contiguous memory and we weren't using the kIOMemoryPhysicallyContiguous option. So, the fix was easy. We added that, and the glitching stopped because ram was then allocated per the uhci requirement.

Unfortunately xnu source is not available, so I can't see if anything has changed. Is is possible that even though we are selecting the kIOMemoryPhysicallyContiguous option, we aren't actually being returned physically contiguous ram under all conditions in Snow Leopard? The user who is seeing this issue has 4gb of ram, but he's running some vmware vms and he says that he only has a few mb of ram free according to activity monitor.

Will this call return non-contiguous ram if it can't find contiguous ram? Are there any known issues relating to this in Snow Leopard?

Thanks

-Dan

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