Re: UVM aobj: Large VM objects.

[David Brownlee <abs%NetBSD.org@localhost>]

On Mon, 6 Mar 2006, YAMAMOTO Takashi wrote:

> > Hi,
> >
> > The Kernel aobject (kernel_object_store) spans (VM_MAX_ADDRESS -
> > VM_MIN_ADDRESS) on all ports. On ia64, the kernel VM range is
> > determined by the size of an IA64 "region". This was inherited from
> > FreeBSD MD code.
> >
> > The maximum number of pages required to map this size overflows type
> > int, even with 16KB page sizes. Would the following ( and possibly
> > more like this to come ) affect other areas of UVM ?
>
> (although i doubt kernel_object really need to cover the entire region,)
> making aobj 64-bit offset clean is a good idea.
>
> however, i don't think long is appropriate here.
> please introduce a 64-bit "page offset" type.
> "typedef voff_t pgoff_t" should be fine.

        Can't we use something similar to vm_offset_t, which is
        appropriately sized for the machine?

        If we are ever going to need it to be 64bit on every arch with 32bit
        physical and virtual addresses then I agree it should be 64bit,
        but otherwise its yet another tiny performance loss/memory
        growth, continuing the pecking to death by ducks...

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