Re: [Qemu-devel] KQEMU Darwin port status?

[Philip Boulain]

On 19 Mar 2007, at 08:49, Mike Kronenberg wrote:
> I have made a empty kext and a dummy client to do some tests on  
> this topics. Boundary crossing is working well, so by now the kext  
> part is ready.
> http://www.kronenberg.org/files/kqemu_poc.zip

Neat, thanks.

> Unfortunately, Apple decided to remove/hide some of the vm_* API  
> (especially vm_map_(un)wire in Tiger. (It was available on Panther.  
> vm_map_user_pageable was never part of Darwin). So any suggestions  
> on how to lock user pages in Darwin would be very welcome.

Mmm, that's rather unhelpful. From my own reading, it looks like the  
Apple-approved way of doing this would be to use an  
IOMemoryDescriptor: initWithAddress() would initialise one which  
represents the appropriate lump of application-space memory  
(vm_address_t, length, direction [1] and task_t [2]); prepare() and  
complete() wire and unwire it respectively; and presumably  
getPhysicalSegment() covers the 'get physical address' part. Using  
this probably requires making the extension a I/O Kit Device Driver,  
but that's just a few extra methods to implement AFAICT.

I'll see if I can make a trivial test for this approach.

Phil
1. kIODirectionOutIn (or InOut) appears suitable here---the kernel- 
side IOKit headers show both as equivilent to VM_PROT_READ |  
VM_PROT_WRITE
2. Looking at the FreeBSD version, that's just "current process", so  
literally current_task()