On Jan 6, 2011, at 11:29 AM, Arnd Bergmann wrote: > On Friday 31 December 2010, Philip Rakity wrote: >> The patch selects ARCH-MMP (as now) but adds the ability >> to also know which specific SoC was chosen. (This is sort of done by choosing the development board today). > > On a larger scale, we try to go in the opposite direction: make it possible to > have kernels run on as many boards as possible by decreasing the code differences > between SoCs and even SoC families. > >>> Your patches will make them mess. >> >> suggest a solution. >> >> The current mechanism of having the development board select the CPU does not seem right. >> One can select a development board for MMP2 and PXA168 and yet the arch files to support each CPU >> are different and not compatible. (for example cache handling). > > The optimal solution would be to make sure that working support for both CPUs can be built into > a single kernel. There is a lot of infrastructure in arch/arm/mm/* that tries to do this, but > I don't know of that actually works for the combination of CPU_MOHAWK and CPU_V6. It does > work for some other combinations of CPU cores though, so it's certainly possible. > For instance, arch/arm/include/asm/cacheflush.h has abstractions to select the cache handling > at boot time. > > To go even further, it might make sense to combine the PXA and MMP platforms, since they already > share some code through the plat-pxa directory. > > Getting it running for MMP with mohawk and v6 cores could be a significant amount of work if > nobody has tries this in that platform, so for now, I would recommend you just keep ARCH_MMP as > a global option in arch/arm/Kconfig for now and add another 'choice' statement in > arch/arm/mach-mmp/Kconfig to select the CPU core, with the board selection depending on that. > Thanks for the suggestion. Let me see if I can implement this. A couple of points first a) current implementation once PXA168/910 is selected will no longer show MMP2 boards so it is also broken. Play around and you will see the issues My proposed patch did the following a) ARCH_MMP is set when PXA168, PXA910 or MMP2 are selected (from arch/arm) b) Board selection uses the PXA168/PXA910/MMP2 to show correct board. If I understand what you are suggesting is the following a) leave ARCH_MMP is system selection alone -- b) move speciific CPU selection to where board selection is now (cpu/arch/mach-mmp) c) what do with development boards ? select all of them for the CPU Type ? Point me to a Kconfig that does what you are suggesting as an example and I can try out the suggestion. > Arnd > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
