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Re: FPU Emulator (Re: Enhanced 2.2.12 MIPS Kernel Sources Available)

To: "Kevin D. Kissell" <kevink@mips.com>, <linux@cthulhu.engr.sgi.com>, <linux-mips@fnet.fr>
Subject: Re: FPU Emulator (Re: Enhanced 2.2.12 MIPS Kernel Sources Available)
From: "Bradley D. LaRonde" <brad@ltc.com>
Date: Thu, 10 Feb 2000 09:49:49 -0500
References: <00d801bf73c9$32d3b820$0ceca8c0@satanas.mips.com>
Thank you.  I will forward this information to the Linux VR group.  Maybe
someone will volunteer.  Or maybe someone on this list?  :-)

Regards,
Brad

----- Original Message -----
From: "Kevin D. Kissell" <kevink@mips.com>
To: "Bradley D. LaRonde" <brad@ltc.com>; <linux@cthulhu.engr.sgi.com>;
<linux-mips@fnet.fr>
Sent: Thursday, February 10, 2000 8:06 AM
Subject: FPU Emulator (Re: Enhanced 2.2.12 MIPS Kernel Sources Available)


> Hey, one reason I wanted to get the code out there
> ASAP was to allow someone to do just that!
>
> The bulk of the emulator lives in its own directory,
> arch/mips/fpu_emulator, and the arch/mips/kernel/traps.c
> hook is very simple.  There are, however, hooks that
> need to be put into context switch, kgdb, and signal support
> code here and there, and these key off some enhancements
> we made to the CPU configuration code (e.g., there is
> a mips_cpu data structure with an options field that
> indicates the presence or absence of an FPU at
> runtime).   In theory, the emulator is capable of executing
> kernel FPU instructions and register register references
> as well as those from user mode, but it's considerably
> more efficient if the kernel knows to reference the simulator
> state instead.  The work to merge all this into the SGI 2.3.xx
> tree should not be too daunting, but it's not something that
> MIPS is likely to take on internally any time soon.
>
>             Regards,
>
>             Kevin K.
>
> -----Original Message-----
> From: Bradley D. LaRonde <brad@ltc.com>
> To: Kevin D. Kissell <kevink@mips.com>; linux@cthulhu.engr.sgi.com
> <linux@cthulhu.engr.sgi.com>; linux-mips@fnet.fr <linux-mips@fnet.fr>
> Date: Thursday, February 10, 2000 11:06 AM
> Subject: Re: Enhanced 2.2.12 MIPS Kernel Sources Available
>
>
> >RFC: What about geting the same FPU emulation into SGI's tree?
> >
> >Regards,
> >Brad
> >
> >----- Original Message -----
> >From: "Kevin D. Kissell" <kevink@mips.com>
> >To: <linux@cthulhu.engr.sgi.com>; <linux-mips@fnet.fr>
> >Sent: Wednesday, February 09, 2000 5:27 PM
> >Subject: Enhanced 2.2.12 MIPS Kernel Sources Available
> >
> >
> >> As many of you will have inferred, MIPS Technologies Inc
> >> has been working on the MIPS/Linux kernel for the past
> >> six months or so, driven by the need for a flexible software
> >> platform for valdiation and characterisation of new MIPS
> >> processor designs.  Relatively early on, we made the difficult
> >> decision not to try to track the SGI Linux repository: It was
> >> too unstable, and the SGI activity is driven by a very
> >> different set of goals.  We therefore took the 2.2.12
> >> kernel sources from kernel.org, and worked from there.
> >> I've shared some of our bug findings and fixes with
> >> the SGI mailing list, and still more of them with Ralf
> >> directly, but a lot of other changes and improvements
> >> have been made that will certainly be of interest to readers
> >> of this list, particularly those targeting non-SGI platforms.
> >>
> >> This kernel supports the new generation of 32-bit MIPS
> >> CPUs with R4K exception models.  This involved fairly
> >> extensive changes to semaphore support and to TLB
> >> and cache management routines.  We know it works on
> >> the MIPS 4Kc, and with appropriate additions to the
> >> table of recognized CPUs in the (revised) CPU probe
> >> code, it should run on the IDT 323xx, and Toshiba TX49
> >> processor families as well.
> >>
> >> It includes an integrated FPU emulator that handles
> >> the full MIPS FP instruction set, and allows FPU-less
> >> CPUs to run standard MIPS/Linux binaries.
> >>
> >> It contains a number of endianness fixes in the kernel
> >> and driver code, and is very stable in both configurations.
> >>
> >> It contains platform support for the Algorithmics P-5064
> >> and MIPS "Atlas" development boards, as well as the
> >> SGI Indy.
> >>
> >> This code is NOT a supported product of MIPS
> >> Technologies Inc.   It is being made available on an
> >> "as is" basis subject to the ususal GPL.  It should be
> >> accessible via anonymous (and blind) FTP for a while at
> >> ftp://ftp.mips.com/incoming/linux.mips.src.01.01.tar.gz
> >> and is archived on the Paralogos MIPS/Linux web site at
> >> http://www.paralogos.com/mipslinux/.  We'd be very interested
> >> in any feedback, experimental results, and enhancements
> >> that any of you may wish to provide, and I will answer
> >> email questions to the extent that my time allows.
> >>
> >>             Regards,
> >>
> >>             Kevin K.
> >> __
> >>
> >> Kevin D. Kissell
> >> MIPS Technologies European Architecture Lab
> >> kevink@mips.com
> >> Tel. +33.4.78.38.70.67
> >> FAX. +33.4.78.38.70.68
> >>
> >
>

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