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Re: IP32 prom crashes due to __pa() funkiness

To: Linux MIPS List <linux-mips@linux-mips.org>
Subject: Re: IP32 prom crashes due to __pa() funkiness
From: Kumba <kumba@gentoo.org>
Date: Sat, 17 Mar 2007 22:04:41 -0400
Cc: Arnaud Giersch <arnaud.giersch@free.fr>
In-reply-to: <87irczzglc.fsf@groumpf.homeip.net>
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References: <45D8B070.7070405@gentoo.org> <cda58cb80703010139y3e5bbb8eqa4d25b75ba658a22@mail.gmail.com> <45FC46F0.3070300@gentoo.org> <87irczzglc.fsf@groumpf.homeip.net>
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Arnaud Giersch wrote:

I don't know if it is the RightWay(TM), but I am running here a fresh
IP32 kernel (l.m.o git updated yesterday).  It was compiled with
CONFIG_BUILD_ELF64=n, and I am using vmlinux.

$ file /boot/vmlinux-2.6.21-rc3-g839fd555 /boot/vmlinux-2.6.21-rc3-g839fd555: ELF 64-bit MSB executable, MIPS, MIPS-IV version 1 (SYSV), statically linked, not stripped

If it makes a difference, I am using arcboot.

I suppose then the question is, which is better for IP32? CONFIG_BUILD_ELF64=y or CONFIG_BUILD_ELF64=n. The reason the o64 hack used to exist, if my memory serves me correctly, was that someone once said that when built and run as a pure 64bit binary converted to 32bit via objcopy, 6 extra insns were run every cycle (I think), introducing unneeded slowdown. This changed to 2 insns by going the o64 route, which involved CONFIG_BUILD_ELF64=n. So 4 less insns technically resulted in a quicker kernel, though the layman might not notice such. I believe that all changed at some point, which is why CONFIG_BUILD_ELF64=y was an A-OK thing prior to the __pa() introduction.

Now I guess we're back to CONFIG_BUILD_ELF64=n? I guess the real question is, which way is the OneWay(TM), RightWay(TM) and OnlyWay(TM)?


Cheers,

--Kumba

--
Gentoo/MIPS Team Lead

"Such is oft the course of deeds that move the wheels of the world: small hands do them because they must, while the eyes of the great are elsewhere." --Elrond

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