[Top] [All Lists]

RE: MIPS 64?

To: "Jun Sun" <>, "Daniel Jacobowitz" <>
Subject: RE: MIPS 64?
From: "Matthew Dharm" <>
Date: Wed, 15 May 2002 15:16:29 -0700
Cc: "Linux-MIPS" <>
Importance: Normal
In-reply-to: <>
I personally think it's long overdue that we really invest some
time/effort in the 64-bit version.  I mean, anything past 0.5 GiB is
really a hack on 32-bit....

I, for one, am willing to lend a pair of hands to this... but I need
to know what needs doing, first.

Could someone give me an overview of how you're supposed to do a
handoff between a 32-bit loader and a 64-bit app?  I'm guessing there
has to be a way to do it, but what I do know about the 64-bit stuff
doesn't show me how this is accomplished (I have visions of UX bits
floating in my head...)


Matthew D. Dharm                            Senior Software Designer
Momentum Computer Inc.                      1815 Aston Ave.  Suite 107
(760) 431-8663 X-115                        Carlsbad, CA 92008-7310
Momentum Works For You            

> -----Original Message-----
> From:
> []On Behalf Of Jun Sun
> Sent: Wednesday, May 15, 2002 3:00 PM
> To: Daniel Jacobowitz
> Cc: Matthew Dharm; Linux-MIPS
> Subject: Re: MIPS 64?
> Daniel Jacobowitz wrote:
> > On Wed, May 15, 2002 at 02:34:47PM -0700, Matthew Dharm wrote:
> >
> >>So... I'm looking at porting Linux to a system with 1.5GiB of RAM.
> >>That kinda blows the 32-bit MIPS port option right out of
> the water...
> >>
> >
> > Not unless you count bits differently than I do... 32-bit
> is 4 GiB.  Is
> > there any reason MIPS has special problems in this area?
> >
> MIPS has lower 2GB fixed for user space.  Then you have
> kseg0, .5GB for cached
> physical address 0-0.5GB, and kseg1, 0.5GB uncached mapping
> of the same area.
>   You can map another 1GB of RAM into kseg2/3, but you will
> then have no space
> left for IO.
> So you really can't do 1.5GB on 32 bit kernel.
> It is interesting that PPC allows one to adjust user space
> size and kernel
> space size.  So on PPC you can get up to 2.5GB system RAM
> with 1GB user space.
> Back to 64bit port, it seems to me much of the 32bit work
> we have done in the
> past a year or so needs to be moved over.  Or better yet,
> if we can clean up
> integer/long issues, we might be able to use 32bit kernel
> code straight for
> 64bit kernel.
> Jun

<Prev in Thread] Current Thread [Next in Thread>