RE: NX support in GNU Mach

[Yuhong Bao]

In fact, even Windows XP SP2 and later had to enable PAE with physical address 
space limited to 4GB in order to enable NX.

32-bit GNU Mach is limited to 1 GB of memory, so NX and Xen support are the 
only uses for PAE on 32-bit GNU Mach.
To actually address more than 1 GB GNU Mach will need to be ported to 64-bit 
(which can sttill run with a 32-bit userspace), or something similar to Linux's 
HIGHMEM will need to be added.

Yuhong Bao

----------------------------------------
> Date: Sun, 15 Mar 2009 23:19:15 +0100
> From: samuel.thibault@ens-lyon.org
> To: yuhongbao_386@hotmail.com
> CC: bug-hurd@gnu.org
> Subject: Re: NX support in GNU Mach
>
> Hello,
>
> Yuhong Bao, le Fri 13 Mar 2009 12:14:56 -0700, a écrit :
>> I heard that PAE support has been recently implemented in GNU Mach.
>
> Yep.
>
>> I think the next step is to add No-Execute (NX) support to GNU Mach.
>
> Oh, that could be useful indeed. The good news is that the user/kernel
> interface already exists: VM_PROT_EXECUTE, it's just not implemented
> yet within gnumach..
>
>
>> I'd also suggest adding support for more then 4 GB of RAM to GNU Mach, but
>> considering that it does not even support more than 1 GB of RAM yet, I'd fix
>> that before trying to support more than 4 GB of RAM. And it is IMO important 
>> to
>> fix, because most of today's PCs have more than 1 GB of RAM, especially 
>> thanks
>> to Vista.
>
> It'd be probably better to just support 64bit processors, which will
> immediately bring support for more than 1GB of RAM. Support for more
> than 1GB of RAM on a 32bit machine is really clumsy. Linux does it, but
> it's really a pain.
>
>> Also important IMO is ACPI support, which will help when implementing
>> SMP support.
>
> Well, the ACPI part for SMP shouldn't be so hard ; SMP itself will be.
>
> Samuel

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