Re: Anyone using PowerPC little-endian mode?
On Thu, Jun 03, 2010 at 06:25:01AM -0600, Gary Thomas wrote: I don't know about today, but my recollection is that the only use of little-endian mode on PowerPC was during the early days attempt to run Windows-NT. You could potentially hit this case by running Mac on Linux. A handful of Mac programs (like early versions of VirtualPC) used this mode. Any that did had to get fixed to run on a PowerMac G5, obviously. I haven't personally tried this, and I wouldn't be shocked to find that MoL chokes on this case for some other reason. I do know that VirtualPC did this because it was G3/G4 only for a while until they rewrote it to not use the little-endian mode. Brad Boyer f...@allandria.com ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Anyone using PowerPC little-endian mode?
Currently the kernel supports processes running in little-endian mode on machines that have a little-endian mode (as opposed to an endian bit in the TLB entry like most embedded PowerPC processors do, which is a much better idea). Little-endian mode comes in two flavours: so-called PowerPC little-endian mode, which works by swizzling the bottom 3 bits of the address, and true little-endian mode, which actually swaps the order of the bytes read from or written to memory. The classic 32-bit processors (603, 604, 750, 74xx, and derivatives) implemented PowerPC little-endian mode, and I think some early 64-bit processors did also. POWER6 and POWER7 implement true little-endian mode. POWER4, PPC970 and POWER5 don't implement any little-endian mode. Is anyone actually using little-endian mode processes on processors that implement PowerPC little-endian mode? One of the ways that we could make the alignment interrupt handler go faster is by removing the code for address swizzling that we have in order to handle PowerPC little-endian mode. If nobody is actually using it, we should remove it and make the code simpler and faster. Paul. ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: Anyone using PowerPC little-endian mode?
On 06/03/2010 06:20 AM, Paul Mackerras wrote: Currently the kernel supports processes running in little-endian mode on machines that have a little-endian mode (as opposed to an endian bit in the TLB entry like most embedded PowerPC processors do, which is a much better idea). Little-endian mode comes in two flavours: so-called PowerPC little-endian mode, which works by swizzling the bottom 3 bits of the address, and true little-endian mode, which actually swaps the order of the bytes read from or written to memory. The classic 32-bit processors (603, 604, 750, 74xx, and derivatives) implemented PowerPC little-endian mode, and I think some early 64-bit processors did also. POWER6 and POWER7 implement true little-endian mode. POWER4, PPC970 and POWER5 don't implement any little-endian mode. Is anyone actually using little-endian mode processes on processors that implement PowerPC little-endian mode? One of the ways that we could make the alignment interrupt handler go faster is by removing the code for address swizzling that we have in order to handle PowerPC little-endian mode. If nobody is actually using it, we should remove it and make the code simpler and faster. I don't know about today, but my recollection is that the only use of little-endian mode on PowerPC was during the early days attempt to run Windows-NT. -- Gary Thomas | Consulting for the MLB Associates |Embedded world ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
