linux-mips
[Top] [All Lists]

Re: mips64 linker bug?

To: <linux-mips@oss.sgi.com>, "Thiemo Seufer" <ica2_ts@csv.ica.uni-stuttgart.de>
Subject: Re: mips64 linker bug?
From: "Kevin D. Kissell" <kevink@mips.com>
Date: Sun, 22 Jul 2001 13:44:37 +0200
References: <20010722131525.L16278@rembrandt.csv.ica.uni-stuttgart.de>
Sender: owner-linux-mips@oss.sgi.com
> Kevin D. Kissell wrote:
> [snip]
> > > An Kernel with 64bit addresses is less compact and likely to run
slower.
> > > OTOH, a 64bit Kernel has certainly some hack value. :-)
> >
> > Note that the 5Kc is one of the new generation of MIPS64 parts
> > that can enable 64-bit integer and floating point instructions without
> > requiring that 64-bit addressing also be enabled in the kernel.
>
> Sorry, but I can't see what's new here. AFAICS this possibility existed
> already in MIPS III.

Sorry if I wasn't clear.  It is only the newer parts that can enable the
use of the 64-bit instructions *in user mode* without also enabling
64-bit addressng.  It's true that MIPS III/IV parts provide access to
those instructions in kernel regardless of the state of the Status.KX
bit,  but in user mode they are only available if the Status.UX bit is set,
enabling 64-bit addressing.  MIPS64 CPU's have an additional
bit in the Status register (Bit 23, "PX") to enable 64-bit instructions
without enabling 64-bit addressing.

            Regards,

            Kevin K.


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