From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41633) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YDFPr-00007l-Cc for qemu-devel@nongnu.org; Mon, 19 Jan 2015 11:43:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YDFPp-00046e-CR for qemu-devel@nongnu.org; Mon, 19 Jan 2015 11:43:02 -0500 Message-ID: <54BD33ED.30702@ilande.co.uk> Date: Mon, 19 Jan 2015 16:42:21 +0000 From: Mark Cave-Ayland MIME-Version: 1.0 References: <1421667328-11800-1-git-send-email-mark.cave-ayland@ilande.co.uk> <1421667328-11800-3-git-send-email-mark.cave-ayland@ilande.co.uk> <54BCFC57.3010709@redhat.com> <54BD1C2D.9070603@suse.de> In-Reply-To: <54BD1C2D.9070603@suse.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH 2/2] m48t59: add mem_base value to m48t59_init_isa() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= , Artyom Tarasenko Cc: Paolo Bonzini , =?UTF-8?B?SGVydsOpIA==?= =?UTF-8?B?UG91c3NpbmVhdQ==?= , qemu-ppc@nongnu.org, qemu-devel , Alexander Graf On 19/01/15 15:01, Andreas Färber wrote: > Am 19.01.2015 um 13:57 schrieb Artyom Tarasenko: >> On Mon, Jan 19, 2015 at 1:45 PM, Paolo Bonzini wrote: >>> On 19/01/2015 12:35, Mark Cave-Ayland wrote: >>>> Similar to m48t59_init(), add a mem_base value so that NVRAM can be mapped via >>>> MMIO rather than ioport if required. >>>> >>>> Signed-off-by: Mark Cave-Ayland >>>> --- >>> >>> Is it really ISA if it's MMIO? In other words, why can't this be a >>> sysbus device? >> >> On physical machines it's EBus, which is pretty much like 8-bit ISA. >> So, I think modelling it as ISA is closer to to the reality. >> But out of curiosity, would it be possible to have a sysbus device >> somewhere in a middle of PCI space? [...] > > Why would you want to use a SysBusDevice in the first place? I > previously discussed with Mark that it should be an EBusDevice, not an > ISADevice or SysBusDevice. IndustryPack is an example of a custom bus > that sits behind a PCI bridge and doesn't need a global variable. I can see this makes logical sense - I guess the reason it hasn't been done was to avoid having to write EBus-specific initialisation code for every device which would only be used on one platform. So you're suggesting that IndustryPack is a way of doing this? > Also, wasn't Hervé's(?) plan to get rid of mem_base completely by always > passing a pointer to ISADevice/ISABus around? It should only be needed > when somewhere NULL is being passed, no? That would definitely be better for wiring things up with -device but wouldn't that involve changing all of the existing ISA devices? ATB, Mark.