Hi, On Tue, Feb 24, 2009 at 03:16:02PM +0100, Sebastian Andrzej Siewior wrote: > Hello PowerPC team, > > I have a Lenny snapshot of a new Debian architecture called gnuspe > located at [0]. I haven't announced it anywhere (until now). It is > called gnuspe because the gcc triplet is powerpc-linux-gnuspe-. This > port is for all PowerPCs which have an E500 core [1]. The main important > differences between PowerPC and this one are:
Are you building userspace with SPE instructions enabled, or are you using only the base power ISA for the binaries? > - the "normal" FPU unit is not present. Instead the APU offers float > point operations. This is _not_ SW-emulation it is HW support but > different at the assembly level. The ABI is also different (there are > no dedicated FPU regs). > - those opcodes (or some of them) have the same binary representation > like AltiVec. The spec forbids AltiVec. No BookE cores have altivec, besides I don't think the base distro uses any altivec since it would not be usable on IBM big iron before power6, nor on 603/604 (G3) systems. > - It is not 100% compatible with the PowerPC ISA. An opcode, lwsync, > is not supported by the core and raises an invalid opcode exception. > This is a core bug. This is not a core bug per se, but somewhat annoying interpretation of the spec by FSL, as far as I know? > In the past I used the normal PowerPC port which was sufficient for most > things, however it got very slowly once it came to floating point. > Starting with gcc 4.2 (I think but starting with Lenny is correct) the > gcc starts using the lwsync opcode more frequently and every C++ program > is effected via libstdc++ as you can see in #495120. Replacing the opcode > in the PowerPc port would cost performance on all other PowerPCs. Another alternative is to have the kernel rewrite the instruction to be a sync instead (which is the expected behaviour on cores not implementing lwsync), when the fault is taken. > Now, I wanted to ask if there are more people that could be interrested > in this port. > > Any comments are welcome. I don't have a personal stake in this, but I think a regular booke port (compiled for softfpu and no SPE) would be more valuable, since that would also run on IBM/AMCC 4xx CPUs. -Olof -- To UNSUBSCRIBE, email to debian-powerpc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
