Re: [PATCH 4/8] jump label: Make arch_jump_label_text_poke_early()optional

[David Miller]

From: Steven Rostedt <rostedt@xxxxxxxxxxx>
Date: Thu, 28 Oct 2010 09:55:52 -0400

> From: David Daney <ddaney@xxxxxxxxxxxxxxxxxx>
> 
> For the forthcoming MIPS jump label support,
> arch_jump_label_text_poke_early() is unneeded as the MIPS NOP
> instruction is already optimal.
> 
> Supply a default implementation that does nothing.  Flag x86 and SPARC
> as having arch_jump_label_text_poke_early().
> 
> Cc: Jason Baron <jbaron@xxxxxxxxxx>
> Cc: David Miller <davem@xxxxxxxxxxxxx>
> Signed-off-by: David Daney <ddaney@xxxxxxxxxxxxxxxxxx>
> LKML-Reference: <1286218615-24011-2-git-send-email-ddaney@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>

On the SPARC side, it's not that the nop isn't optimal, on sparc it's
always 0x01000000.  The issue is that when written an I-cache flush is
necessary using a 'flushi' instruction.

Does MIPS not need a flush when poking instructions?  I find this hard
to believe, although it's been some time since I last touched that
architecture :-)
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