Re: IOMallocAligned casuses kernel trap
Re: IOMallocAligned casuses kernel trap
- Subject: Re: IOMallocAligned casuses kernel trap
- From: Michael Smith <email@hidden>
- Date: Wed, 16 Aug 2006 02:15:34 -0700
On Aug 15, 2006, at 12:02 PM, email@hidden wrote:
I am writing a PCI device driver to transfer data from the board
memory
to the system memory. I am trying to allocate a wired page to transfer
data.
Typically you don't want to do this; instead you would transfer
directly to
your client's memory.
I do not have any code for transfer yet. After adding
set_Page = (UInt32*)IOMallocAligned(PAGE_SIZE,PAGE_SIZE) line, when I
loaded the kext kernel crashed. I then tried IOMalloc as well as
IOMallocPageable to check if they work. All of them result in kernel
crash. Can anyone tell what I am doing wrong here?
Not with so little information, no.
I read in kernel
programming on Mac (pdf document) that IOMallocAligned should not be
used. But that document did not say anything about IOMallocPageable.
You read a document that told you not to do something, so you went ahead
and did it anyway?
If you're reading documents, I encourage you to read the one that
explains
two-machine debugging. You're not going to get very far developing a
device
driver without some capacity for debugging your mistakes, and this
mailing list is no substitute for the proper tools.
I would also encourage you to explore the large amount of I/O Kit device
driver source available on the web, and look for examples of the sort of
things that your driver needs to do. If you're not willing or able
to share
your source code with us, there is little or no help that we can
offer in return
when confronted with questions like the one you've asked above.
= Mike
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