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Date: Fri, 14 Oct 2011 11:51:46 -0700
From: Jeremy Fitzhardinge <jeremy@goop.org>
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To: "H. Peter Anvin" <hpa@zytor.com>
CC: Jason Baron <jbaron@redhat.com>, Peter Zijlstra <peterz@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@elte.hu>, the arch/x86 maintainers <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Nick Piggin <npiggin@kernel.dk>, Avi Kivity <avi@redhat.com>,
        Marcelo Tosatti <mtosatti@redhat.com>, KVM <kvm@vger.kernel.org>,
        Andi Kleen <andi@firstfloor.org>,
        Xen Devel <xen-devel@lists.xensource.com>,
        Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
        konrad.wilk@oracle.com, rth@redhat.com
Subject: Re: [PATCH RFC V5 00/11] Paravirtualized ticketlocks
References: <cover.1318466916.git.jeremy.fitzhardinge@citrix.com> <1318503245.24856.12.camel@twins> <4E971580.6030300@goop.org> <20111014141701.GA2433@redhat.com> <4E986B2B.60803@goop.org> <20111014183539.GE2433@redhat.com> <4E9881A6.9050106@zytor.com>
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On 10/14/2011 11:38 AM, H. Peter Anvin wrote:
> On 10/14/2011 11:35 AM, Jason Baron wrote:
>> A nice featuer of jump labels, is that it allows the various branches
>> (currently we only support 2), to be written in c code (as opposed to asm),
>> which means you can write your code as you normally would and access any
>> parameters as you normally would - hopefully, making the code pretty
>> readable as well.
>>
>> I hope this better clarifies the use-cases for the various mechanisms.
>>
> There is an important subcase which might be handy which would be to
> allow direct patching of call instructions instead of using indirect calls.

Right, that's how the pvops patching is primarily used.

    J