From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 89A681A0260 for ; Sat, 28 Mar 2015 21:57:21 +1100 (AEDT) Message-ID: <1427540240.7547.1.camel@ellerman.id.au> Subject: Re: [PATCH] powerpc/powernv: Remove powernv RTAS support From: Michael Ellerman To: "Aneesh Kumar K.V" Date: Sat, 28 Mar 2015 21:57:20 +1100 In-Reply-To: <87k2y24n4f.fsf@linux.vnet.ibm.com> References: <1426141631-10741-1-git-send-email-mpe@ellerman.id.au> <87k2y24n4f.fsf@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, dja@axtens.net List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2015-03-27 at 18:24 +0530, Aneesh Kumar K.V wrote: > Michael Ellerman writes: > > > The powernv code has some conditional support for running on bare metal > > machines that have no OPAL firmware, but provide RTAS. > > > > No released machines ever supported that, and even in the lab it was > > just a transitional hack in the days when OPAL was still being > > developed. > > > > So remove the code. > > So when we select CONFIG_PPC_PSERIES, we end up selecting > CONFIG_PPC_RTAS. What is the expected behaviour there for powernv ? After this patch, the expected behaviour is that the powernv platform code won't use RTAS, even if it's there. And that's fine because no real powernv machines have RTAS. In a perfect world the RTAS code would be isolated in platforms/pseries, but it's used on other platforms, so it's a bit messier than that. But the expected behaviour is that the powernv code won't use RTAS, even if the code is still built in. Is that what you meant? > Can we use RTAS call from powernv code if rtas node is present in device > tree ? Yes you can, if you build with CONFIG_PPC_RTAS=y. Though when I add a powernv_defconfig (soon), it won't have CONFIG_PPC_RTAS. > Or do we want to make sure powernv always use OPAL call ? It depends what you mean by "powernv". Once this patch is applied the powernv *platform* code will not use RTAS. There may still be other code that can be built into a kernel and booted on powernv that then uses RTAS. That's fine, if it makes sense for someone, I don't think we need to prevent that happening. > For example, right now we will use rtas_node get-term-char and > put-term-char even with this patch applied. Well you will *if* your machine has RTAS, and you have CONFIG_HVC_RTAS=y and/or CONFIG_UDBG_RTAS_CONSOLE=y. So I think that's fine? cheers