On Tue, Feb 13, 2018 at 10:09 AM, Greentime Hu <green.hu@xxxxxxxxx> wrote: > This patch includes the exception/interrupt entries, pt_reg structure and > related accessors. > > /* Unaligned accessing handling*/ > Andes processors cannot load/store information which is not naturally > aligned on the bus, i.e., loading a 4 byte data whose start address must > be divisible by 4. If unaligned data accessing is happened, data > unaligned exception will be triggered and user will get SIGSEGV or > kernel oops according to the unaligned address. In order to make user be > able to load/store data from an unaligned address, software load/store > emulation is implemented in arch/nds32/mm/alignment.c to address data > unaligned exception. > > Unaligned accessing handling is disabled by default because it is not a > normal case. User can enable this feature by following steps. > > A. Compile time: > 1. Enable kernel config CONFIG_ALIGNMENT_TRAP > B. Run time: > 1. Enter /proc/sys/nds32/unaligned_acess folder > 2. Write 1 to file enable_mode to enable unaligned accessing > handling. User can disable it by writing 0 to this file. > 3. Write 1 to file debug to show which unaligned address is under > processing. User can disable it by writing 0 to this file. > > However, unaligned accessing handler cannot work if this unaligned > address is not accessible such as protection violation. On this > condition, the default behaviors for addressing data unaligned exception > still happen > > Signed-off-by: Vincent Chen <vincentc@xxxxxxxxxxxxx> > Signed-off-by: Greentime Hu <greentime@xxxxxxxxxxxxx> Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
