Date: Thu, 30 Jan 2003 15:07:04 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: "M. Warner Losh" <imp@bsdimp.com> Cc: marcel@xcllnt.net, jmallett@freebsd.org, benno@freebsd.org, current@freebsd.org Subject: Re: Patch to teach config(8) about "platforms". Message-ID: <3E39B018.365A8D65@mindspring.com> References: <20030129100411.GA3272@dhcp01.pn.xcllnt.net> <20030129115542.A79257@FreeBSD.org> <20030129204744.GC5416@dhcp01.pn.xcllnt.net> <20030130.101512.83728709.imp@bsdimp.com>
next in thread | previous in thread | raw e-mail | index | archive | help
"M. Warner Losh" wrote: > In message: <20030129204744.GC5416@dhcp01.pn.xcllnt.net> > Marcel Moolenaar <marcel@xcllnt.net> writes: > : Alpha has multiple platforms, but it has not been made explicit. > : pc98 is an alternate platform for i386. And we have PowerPC and > : mips. > > Keep in mind that for mips you have two different architectures: > mipsel and mips(eb). I keep harping on this because you cannot run > mipsel binaries on mipseb kernels (please ignore that some mips cpu > can, in theory do this, since no free OS has climbed that mountain). > You'll need different binaries (packages) for mips and mipsel. PPC has this same thing: byte order is controlled in software. The normal thing to do for this is to pick "one true byte order", but then you may lose access to the host system software that may otherwise be possible to run in binary compatability mode. Actually, as part of the task switch code, it's possible to switch orders on a per task basis, or even run the kernel in one order, and user tasks in another (given appropriate wrapping of the system call arguments which are larger than a byte). My general recommendation for the PPC, actually, is network byte order (Motorolla byte order), since if you are running something manufactured before the PPC620 chip, you actually pay a penalty in performance for running Intel byte order. I never got hold of any documentation claims, one way or the other, for the MIPS, on which order it prefers, or if it actually doesn't have a preference, like older PPC processors. That said, the point about needing a different userland is really one about binary compatability, and how hard your willing to work in order to achieve it, or if you care at all (e.g. the DEC systems ran in VAX byte order, which is Intel byte order, but you aren't going to be able to run Ultrix programs in an emulator, without an incredible amount of effort and/or pirating library files). -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3E39B018.365A8D65>