Re: 64bit GNU Mach

[Richard Braun]

On Mon, Apr 02, 2012 at 02:39:05PM +0200, Samuel Thibault wrote:
> > I don't see the relation with segmentation and the 4GiB split.
> 
> I said: "to avoid the trick", i.e. just use 32bit pointers, to just use
> the same type as in userland as you suggested.
> 
> > What is the layout you expect for the kernel space ? First 4 GiB user
> > then kernel ?
> 
> First 4GiB user, last 4GiB kernel.
> 
> > And you thought of segmentation to implicitely shift addresses ?
> 
> Again, there is no segmentation in x86_64.

I was wondering why you referred to segmentation in the first place.
I guess segmentation is what you referred to as "the trick". It wasn't
a suggestion :).

> > IMHO, changing GNU Mach to cleanly convert port names where needed
> > remains the sane choice.
> 
> That is, use 32bit port names for userland, and convert to 64bit port
> addresses for kernelland. But that can only work if using different
> types.

I believe we're thinking of two different things here. My current idea
of the solution is to directly convert names (32-bits) to ports or other
IPC objects (e.g. port sets, 64-bits). You may be thinking of converting
user names (32-bits) to kernel names (64-bits), then kernel names to IPC
objects. Am I right ?

-- 
Richard Braun