Hi, On Sat, Jan 07, 2017 at 05:38:32PM +0000, Russell King - ARM Linux wrote: > On Sat, Jan 07, 2017 at 10:52:28PM +0530, afzal mohammed wrote:
> > TODO: > > Kill off VECTORS_BASE completely - this would require to handle MMU > > case as well as ARM_MPU scenario dynamically. > Why do you think MMU doesn't already handle it? i meant here w.r.t displaying vector base address in arch/arm/mm/init.c, i.e. dynamically get it based on Hivecs setting as either 0xffff0000 or 0x00000000 > > > config VECTORS_BASE > > hex > > - default 0xffff0000 if MMU || CPU_HIGH_VECTOR > > - default DRAM_BASE if REMAP_VECTORS_TO_RAM > > + default 0xffff0000 if MMU > > default 0x00000000 > > When MMU=y, the resulting VECTORS_BASE is always 0xffff0000. The only > case where this ends up zero after your change is when MMU=n. > The MMU case does have to cater for CPUs wanting vectors at 0xffff0000 > and at 0x00000000, and this is handled via the page tables - but this > has nothing to do with CONFIG_VECTORS_BASE. CONFIG_VECTORS_BASE > exists primarily for noMMU. i had thought that for MMU case if Hivecs is not enabled, CONFIG_VECTOR_BASE has to be considered as 0x00000000 at least for the purpose of displaying exception base address. One thing i have not yet understood is how CPU can take exception with it base address as 0x00000000 (for Hivecs not enabled case) virtual address as it is below Kernel memory map. > For the Berlin and mm/dump code, we could very easily just have a > #define VECTORS_BASE 0xffff0000 in a header file and drop the CONFIG_ > prefix. Okay, thanks for the tip. Regards afzal
