Hi Arnd, On Wed, Mar 28, 2018 at 09:40:49AM +0200, Arnd Bergmann wrote: > Ok, thanks for the clarification. Obviously if they are mutually incompatible, > there is no point in using a common kernel, so your current version is > absolutely fine, and this is similar to how we cannot have a common kernel > between ARMv5, ARMv7-A and ARMv7-M, which are all incompatible > at the kernel level. Yes. > One more question for my understanding: Are the three types of ck8xx > CPUs mutually incompatible in user space as well, or are the differences > only for the kernel? For the ARM example, ARMv5 and ARMv7 > fundamentally require separate kernels, but both can run user space > programs built for ARMv5. -mcpu=ck807 app could run on ck807, ck810, ck860. -mcpu=ck810 app could run on ck807, ck810, ck860. -mcpu=ck860 app only run on ck860. They are all incompatible at the kernel level. Best Regards Guo Ren