PDF version - ARM Information Center

4.2 Tools configurationMigrating a software applicationSeveral compiler toolchains exist which support both ARM and PPC architectures.Vendors such as Greenhills and CodeSourcery, for instance, sell such products.If you are already using a toolchain which supports ARM as a target architecture, theeasiest option is to continue with the same tools.In general, very little of the configuration of the tools will need to change beyond thefollowing.Memory map, code and data placementAny options which relate to particular target PPC architectures, platforms,processors or boards. When deciding on the ARM options, it is good practice tobe as specific as possible with respect to the processor and architecture you areusing.If your application uses floating point, then you will need to configure carefully foreither hardware floating point or soft emulation.There is also the option of using the ARM RealView tools. Clearly, more significantreconfiguration will be required here and you should refer to the RealView documentation(all available on ARM’s website) for further information on this.More information on support for GNU tools can be found here:http://www.arm.com/community/software-enablement/linux.php4.3 Operating systemMay PPC-based systems use the Linux operating system. There are several versions ofthis available for the ARM architecture. Details of Linux support on ARM can be foundhere:http://www.arm.com/community/software-enablement/linux.php4.4 StartupBoth processors will exit reset with in privileged mode with interrupts disabled.ARM processors will reset with the MMU disabled, giving a flat virtual-physical addressmapping with caches disabled. PPC processors will boot with a single preset TLB entrywhich maps the top 4KB of the effective address range to the top 4KB of the real addressrange.Reset software should carry out the following:1. Invalidate instruction and data caches (if the implementation requires it)2. Perform any memory re-mapping required3. Initialize system memory for operating system or application code4. Initialize the system stack pointer5. Initialize the exception vector table6. Initialize other processor registers as required7. Initialize on-chip and off-chip peripherals8. Transfer control to the operating system or applicationApplication Note 245 Copyright © 2012 ARM Limited. All rights reserved. 27ARM DAI 0245B