From mboxrd@z Thu Jan 1 00:00:00 1970 Message-Id: <9902151757.AA75924@marc.watson.ibm.com> To: Benjamin Herrenschmidt Cc: linuxppc-dev@lists.linuxppc.org Subject: Re: bootstrap stuffs In-Reply-To: Message from Benjamin Herrenschmidt of "Sun, 14 Feb 1999 19:58:05 +0100." <19990214195805.018190@smtp.calvacom.fr> Date: Mon, 15 Feb 1999 12:57:34 -0500 From: David Edelsohn Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: >>>>> Benjamin Herrenschmidt writes: Benjamin> On Sun, Feb 14, 1999, David Edelsohn wrote: >> For correctness, "sync" must be used, but for best performance, >> "sync" should be used sparingly, only when necessary. Benjamin> Ok thanks. In this specific case (jump to bootstrap), I don't really care Benjamin> about the performance loss introduced by a sync, I'll keep one just after Benjamin> the mtmsr to make sure that the interrupt switch is fully done before I Benjamin> hack with srr0 and the MMU. "isync" is used to discard instruction pre-fetch and ensure that all previous instructions have occurred. isync is not necessary for your situation either. As Gabriel correctly explained, a "sync" instruction may be necessary before interrupts are enabled if some off-chip operation, like modifying an interrupt controller on the bus, was performed. That is because of the bus operations which need to complete before interrupts can be enabled, not because of the enabling itself. David [[ This message was sent via the linuxppc-dev mailing list. Replies are ]] [[ not forced back to the list, so be sure to Cc linuxppc-dev if your ]] [[ reply is of general interest. To unsubscribe from linuxppc-dev, send ]] [[ the message 'unsubscribe' to linuxppc-dev-request@lists.linuxppc.org ]]