From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3BAA4F46.1020002@mc.com> Date: Thu, 20 Sep 2001 16:19:18 -0400 From: Mark Salisbury MIME-Version: 1.0 To: Holger Bettag , linuxppc-dev@lists.linuxppc.org Subject: Re: ppc LE questions (seeking help hand info pointers) References: <20010920171002.37DCA2B54A@marcus.pants.nu> <3BAA363B.5010400@mc.com> <8xlmj9psnw.fsf@s62.informatik.uni-bremen.de> Content-Type: text/plain; charset=us-ascii; format=flowed Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: Holger Bettag wrote: > Mark Salisbury writes: > > [... linux in ppc little endian mode ...] > >>well, this is in the context of a multi-CPU type (x86/ppc, sparc/ppc, >>ppc/ppc, mips/ppc) shared memory multicomputer. >> >>when dealing w/ direct mapped, shared memory, uniformity of endian-ness >>makes many multicomputer problems easier to solve.(not to mention easier >>for the customer to program...) >> >> > You are aware that a PPC in little endian mode is merely tricking with the > low order address bits, but does not actually lay out its data in a little > endian fashion in physical memory? > not according to section 3.1 of the motorola ppc "green book" according to that it is a sort of munged le representation, which thanks to a "one trick pony" PCI bridge looks like standard LE to the PCI based x86 host. understand please that what I am proposing is a config option. as a sub-architecture port. it would not affect any code that it didn't absolutely need to, and would only be compiled if sombody selected that particular config. I am _NOT_ suggesting running pmacs in LE mode. as in: ppc--- |-- PREP |-- CHRP |-- MAC |-- MERCURY --- |-- Big Endian |-- Little Endian -- /*------------------------------------------------** ** Mark Salisbury | Mercury Computer Systems ** ** mbs@mc.com | System OS - Kernel Team ** **------------------------------------------------** ** Infinite Justice is niether. ** **------------------------------------------------*/ ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/