[U-Boot] [PATCH v4 3/6] ARM: Add macros.h to be used in assembler file.

Jean-Christophe PLAGNIOL-VILLARD
2009-07-07T22:07:10Z

On 23:28 Tue 07 Jul , Wolfgang Denk wrote:
> Dear Jean-Christophe PLAGNIOL-VILLARD,
>
> In message <20090707202432.GK30172@game.jcrosoft.org> you wrote:
> >
> > > > + * These macros provide a convenient way to write 8, 16 and 32 bit data
> > > > + * to any address.
> > >
> > > I think this comment might be wrong. It should probably read "... to
> > > any _memory_ address". Using these macros to access device registers
> > > and the like is probably nore recommended?
> > you can access cpu register without problem with these macros
>
> Is it guaranteed that none of the existing ARM architectures and all
> the plethora of their specific implementations of the zillions of
> SoCs do not require any form of memory barrier instructions when
> accessing device registers? Even when these are external peripherals
> on some external bus?
>
> Sorry for such a stupid question about things that are eventually
> obvious to you, but I don't know ARM processors that well...
you may need it in specific case as cache, tlb, co-processor or smp
otherwise you do not need it

so normaly no-need for register access

Best Regards,
J.