On 03/28/2013 05:04 PM, Alexander Graf wrote: > > On 28.03.2013, at 16:10, Fabien Chouteau wrote: > >> On 03/28/2013 12:46 PM, Alexander Graf wrote: >>> >>> On 28.03.2013, at 12:42, Fabien Chouteau wrote: >>> >>>> >>>> While working on a patch to remove env->hreset_excp_prefix, I'm looking >>>> at which instruction should be the fetched first at power-on. I'm lost >>>> in all the PPC version and configuration, can anyone (Alex :) can help >>>> me with this mess? >>> >>> Phew - I'd say just keep the targets you don't know exactly as they are :). >>> That way you at least don't break anything that wasn't broken before. >>> >>> For the targets where you do know better (like 7x0), change its behavior to >>> be correct according to the respective spec. >>> >> >> Here's what I found in the UM of almost all the cores supported by QEMU: >> >> Every CPU should start at the hreset address (i.e. excp_prefix + 0x100). >> >> However, some cores don't have a hreset exception (4xx and Book E (e200, >> e500)), those cores start at 0xFFFF_FFFC. > > At least the G5 and I think also more recent POWER CPUs have either a small > command stream or a full blown service processor that initialize initial CPU > state like the PC. So there, the CPU starts at a board defined address. >
You're right, if the start address doesn't follow core's specification, it's up to the board. > I don't think we need to worry too much about that for now though. > The problem is that my patch may break support of some platforms, we will have to fix the boards later on. -- Fabien Chouteau
