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

All,
 
First I'd like to thank everyone for their help with this issue.  I was really pleasantly surprised by both the quality and
timeliness of the responses I received.
 
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.
 
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.
 
Thanks again everyone for all your help,
Dave Canfield

From: Garth Cummings [mailto:email@hidden]
Sent: Friday, October 06, 2006 2:01 PM
To: Dave Canfield
Cc: email@hidden
Subject: Re: Kernel panic on Intel based Mac with more than 2GB of memory

Hi Dave,

On Oct 6, 2006, at 1:33 PM, Dave Canfield wrote:

We have a universal binary driver for a SATA HBA that seems to work fine
unless its running on an Intel Mac with more than 2GB of memory
installed.  If there is more than 2GB of memory the system eventually
will panic with the following message in the panic log:

panic(cpu 3 caller 0x003A1D25): getPhysicalSegment() out of 32b range
0x100000000, len 0x8000, class IOGeneralMemoryDescriptor

The problem is that getPhysicalSegment returns a 32 bit address. The panic means that the physical address won't fit in 32 bits, which is the case on Mac Pro systems with more than 2.5 GB of physical memory.

Depending on what you're doing, you need to move to using IODMACommand, or use getPhysicalSegment64. These functions are new as of the Mac Pro but work on all 64-bit capable machines as of 10.4.8.

If you need to support machines older than 10.4.8 (duh!) you'll need to have a KEXT that uses the old API that loads on those systems and a separate KEXT that uses the new API for newer systems. Each KEXT will have to have its own CFBundleIdentifier, and one KEXT can live in the PlugIns directory within the other for ease of installation. Use the OSBundleLibraries version numbers to control which KEXT loads on which OS versions.

If you drop a line to <email@hidden> we can get you a sample PCI driver that shows how to use IODMACommand.

--gc
____________________________________________________________________
Garth Cummings  email@hidden
Sr. Software Engineer
Apple Developer Technical Support



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 >Re: Kernel panic on Intel based Mac with more than 2GB of memory (From: Garth Cummings <email@hidden>)



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