From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44509) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aKCDM-00038B-Ce for qemu-devel@nongnu.org; Fri, 15 Jan 2016 16:47:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aKCDJ-0002q8-3V for qemu-devel@nongnu.org; Fri, 15 Jan 2016 16:47:24 -0500 Received: from mail-qg0-x244.google.com ([2607:f8b0:400d:c04::244]:32977) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aKCDI-0002q4-VW for qemu-devel@nongnu.org; Fri, 15 Jan 2016 16:47:21 -0500 Received: by mail-qg0-x244.google.com with SMTP id o11so47670567qge.0 for ; Fri, 15 Jan 2016 13:47:20 -0800 (PST) Sender: Richard Henderson References: <5699346C.9030402@twiddle.net> From: Richard Henderson Message-ID: <569968E5.7010901@twiddle.net> Date: Fri, 15 Jan 2016 13:47:17 -0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 12/25] target-sparc: Add MMU_REAL_IDX List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Artyom Tarasenko Cc: Mark Cave-Ayland , qemu-devel , Aurelien Jarno On 01/15/2016 12:32 PM, Artyom Tarasenko wrote: >> If we ever properly implement a sun4v platform, we will implement the bulk of >> the hypervisor within qemu itself, for speed. At which point REAL will in fact >> undergo that final layer of translation exactly as expected. >> >> I think the naming is exactly correct, for the current sun4u implementation. > > But sun4u has neither real mode nor any ASI having "real" as a part of > its name, no? Correct-ish. The ASI is called ASI_PHYS_USE_EC. But it has the same number as ASI_REAL. When there's a conflict I'm preferring the newer names. I think that it will cause less confusion in the end. > I thought it is much easier to implement the RA translation than the hypervisor, > but maybe implementing the hypervisor is not as complex as I thought. > > Indeed, your variant would be more performant. > In any case it looks like an interesting challenge. The Alpha PALcode layer (equivalent to the sun4v hypervisor) is 99% implemented in qemu, and performs significantly better because of it. There are a few stubs in the qemu bios calling into some special helpers; I'd expect OpenBIOS for qemu to be the same. r~