Re: Kernel panic on Intel based Mac with more than 2GB of memory

Subject: Re: Kernel panic on Intel based Mac with more than 2GB of memory

From: Chris Sarcone <email@hidden>

Date: Mon, 9 Oct 2006 15:06:33 -0700

Delivered-to: email@hidden

Dave --

Since the driver I'm working on is a universal binary what I've decided to do is to conditionally compile it to make

a call to getPhysicalSegment() when compiled for the PPC platform and to use the new call, getPhysicalSegment64()

when compiling for the Intel platform. If I understand Garth's description of the problem, this should result in a

driver that will run correctly on Intel platforms regardless of the OS version or how much memory is in the system

and should work OK on PPC systems as long as they don't have more than 2.5GB of memory.

You should be using IODMACommand. It works across 32-bit and 64-bit systems and abstracts away any code changes required for things like bounce-buffering, DART, etc. Future x86 hardware may have a DART and using getPhysicalSegment64() will not return a DART-based address, but a physical memory address.

Put another way, getPhysicalSegment64 returns un-I/O-mapped physical addreses, ie. what the processor bus uses.

I've been testing a driver built this way on a MacPro and so far so good, I haven't tried it yet on a PPC based Mac

yet. If anyone knows of a reason (besides not working on PPC based Mac with more than 2.5GB of memory) I

would appreciate hearing from you.

See above.

-- Chris

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References:
	>RE: Kernel panic on Intel based Mac with more than 2GB of memory (From: "Dave Canfield" <email@hidden>)