Date: Tue, 14 Dec 1999 22:47:29 +0100 From: Wilko Bulte <wilko@yedi.iaf.nl> To: Jason Thorpe <thorpej@nas.nasa.gov> Cc: FreeBSD-alpha mailing list <freebsd-alpha@FreeBSD.ORG> Subject: Re: use of -mcpu=21164a Message-ID: <19991214224728.A36085@yedi.iaf.nl> In-Reply-To: <199912142109.NAA29906@lestat.nas.nasa.gov>; from thorpej@nas.nasa.gov on Tue, Dec 14, 1999 at 01:09:39PM -0800 References: <199912142109.NAA29906@lestat.nas.nasa.gov>
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On Tue, Dec 14, 1999 at 01:09:39PM -0800, Jason Thorpe wrote:
> On Tue, 14 Dec 1999 21:39:15 +0100
> Wilko Bulte <wilko@yedi.iaf.nl> wrote:
>
> > Will adding -mcpu=21164a to CFLAGS in /etc/make.conf
> > result in code not running on EV4/21064 CPUs?
>
> The Alpha Architecture specifies that user programs can expect the kernel
> to emulate BWX, so it should work, albeit a bit more slowly in the event
> that BWX is actually used.
OK.
> Also, your assembler has to do the right thing; gas will treat the BWX
> instructions are macros and open-code the equivalent in EV4 instructions
> unless it is explicitly in EV56 (or greater) mode.
So, in case of -mcpu=21164a gas will generate BWX and if -mcpu=21164a
is omitted it will open-code in EV4 instructions?
> If your compiler is targeted correctly, the assembler will behave properly.
> If not, you'll have to pass additional flags.
Time to explain where I'm coming from:
what if I generate 'netboot' on a Miata with mcpu=m21164a and want to
use the generated netboot on a Sandpiper (EV4)? There is no kernel (yet)
to emulate BWX so I lose, right?
Thanks,
--
Wilko Bulte Arnhem, The Netherlands - The FreeBSD Project
WWW : http://www.tcja.nl http://www.freebsd.org
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