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Date:   Mon, 04 Oct 2010 10:43:07 -0700
From:   David Daney <ddaney@caviumnetworks.com>
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To:     Rabin Vincent <rabin@rab.in>
CC:     linux-mips@linux-mips.org, ralf@linux-mips.org,
        linux-kernel@vger.kernel.org, rostedt@goodmis.org,
        jbaron@redhat.com, David Miller <davem@davemloft.net>
Subject: Re: [PATCH] jump label: Add MIPS support.
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On 10/03/2010 11:15 AM, Rabin Vincent wrote:
> On Tue, Sep 28, 2010 at 11:40 PM, David Daney<ddaney@caviumnetworks.com>  wrote:
>> +void arch_jump_label_text_poke_early(jump_label_t addr)
>> +{
>> +       union mips_instruction *insn_p =
>> +               (union mips_instruction *)(unsigned long)addr;
>> +
>> +       insn_p->word = 0; /* nop */
>> +       flush_icache_range((unsigned long)insn_p,
>> +                          (unsigned long)insn_p + sizeof(*insn_p));
>> +}
>
> Can't this function be a no-op on MIPS?  This seems to be
> used on x86 to patch in the optimal nop instruction, but
> on MIPS the optimal/only nop instruction should already
> be in place at build time.  Same thing for the SPARC
> implementation.
>

Yes, I think you are correct.

On MIPS the NOP is already optimal.  I will respin the MIPS patch to 
make arch_jump_label_text_poke_early() be empty.

davem wasn't CCed on the original message, so I added him.  I would 
defer to him on the SPARC version.


Thanks,
David Daney