Paul R.Potts writes:

userland_mem_desc = IOMemoryDescriptor::withAddress (

user_space_pointer,

(unsigned long) user_space_size,

kIODirectionIn);

<..>

However, it appears that an arbitrary point, somewhere between 700

words and 1000 words, the kernel will always crash. (I have not used

trial-and-error to narrow it down to the exact count; reading up to 700

or 2800 bytes into the block succeeds; reading 1000 words fails).

Mac's have 4096 byte pages, so it sounds like you're crashing when you cross a page boundary. What is "user_space_size" for your experiments? Have you verified that the kernel is not attempting to access data "user_space_size" bytes past the beginning of the segment? Drew _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.