From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jun Nakajima Date: Wed, 28 Jun 2000 13:57:10 +0000 Subject: Re: [Linux-ia64] Using f6-f11 floating-point registers Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: linux-ia64@vger.kernel.org Well, I was just wondering because your (with Don) viewgraphs "IA-64 Linux Kernel Internals" (on the IA-64 Linux Web home page) says (p. 9) "considering a change to only provide f6-f11 to the compiler for integer multiply and divide", and I wanted to know how serious you were about it. David Mosberger wrote: >=20 > >>>>> On Tue, 27 Jun 2000 18:02:09 -0400, Jun Nakajima said: >=20 > Jun> At this point, the kernel is using more than f6-f11 > Jun> floating-point registers (using -mfixed-range=F10-f15,f32-f127, > Jun> i.e. those are *not* available to the kernel, but the others, > Jun> like f16-f31 are). >=20 > If the compiler or someone writing assembly code thinks it's > beneficial to use a preserved fp register, we should let them use it. > Of course, they'll have to explicitly save/restore the register before > using it, but there may well be cases where this is beneficial, so we > shouldn't prevent it for no good reason. >=20 > Jun> When do we support the reduced FP model (EL_IA_64_REDUCEFP), > Jun> where only f6-f11 are used by the kernel? >=20 > For the record, I have no plans to adopt the REDUCEFP model. I want > to reserve the right for kernel developers to tweak the kernel > register usage without having to talk to a standards body. Sorry. >=20 > --david --=20 Jun U Nakajima Core OS Development SCO/Murray Hill, NJ