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Date:   Tue, 17 Dec 2019 11:26:09 +1100 (AEDT)
From:   Finn Thain <fthain@telegraphics.com.au>
To:     Geert Uytterhoeven <geert@linux-m68k.org>
cc:     Brad Boyer <flar@allandria.com>,
        John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
        linux-m68k <linux-m68k@lists.linux-m68k.org>,
        Debian m68k <debian-68k@lists.debian.org>
Subject: Re: Using more than 1 GB in qemu-m68k-system
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On Sun, 15 Dec 2019, Geert Uytterhoeven wrote:

> Hi Brad,
> 
> On Sun, Dec 15, 2019 at 3:19 AM Brad Boyer <flar@allandria.com> wrote:
> > We could probably emulate a fake NuBus card in qemu that is just 
> > memory in the super slot space for that card. Can a regular driver add 
> > RAM, or would we have to detect that in the core code somewhere?
> 
> I think a regular driver can do that, if CONFIG_MEMORY_HOTPLUG=y. 
> However, the latter depends on CONFIG_SPARSEMEM.
> 
> The early core code can just call memblock_add(), though.
> 

The nubus subsystem isn't available during early boot. The regular driver 
option might be the best option.

BTW, the Nubus memory mapping done in arch/m68k/kernel/head.S (0xf8000000 
through 0xffffffff) covers the standard slot space but not the super slot 
space.

> Gr{oetje,eeting}s,
> 
>                         Geert
> 
>