From: Sam Ravnborg <sam@xxxxxxxxxxxx>
Date: Sun, 20 May 2012 22:44:47 +0200
> This is what I came up with - on top of the other patches I sent
> which introduced flushi().
> Only RFC for now - I plan to submit a longer set
> of patches that does most of the work to allow leon
> to be used in parallel with the sun platfroms.
Looks great. If you want to get fancy you can write a macro for the
whole section dance and LEON insn entry stuff.
> The sparc64 code I copied the run-time patching from used
> the following sequence for flushing the ICache:
>
> wmb();
> __asm__ __volatile__("flush %0" : : "r" (addr + 0));
>
> Compare this to the flushi() variant:
> #define flushi(addr) __asm__ __volatile__ ("flush %0" : : "r" (addr) : "memory")
>
> As far as I understand the macros "wmb()" is just another way to tell
> gcc what it may do. And the "memory" clobber in flushi()
> serve the same purpose as wmb().
>
> On sparc64 wmb() is: __asm__ __volatile__("":::"memory")
>
> One could introduce flushi() in the relevant functions in setup_64.c..
On sparc64wmb() used to actually do something, with a membar (MEMory
BARrier) instruction, which sparc32 doesn't have and doesn't need.
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