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Date: Thu, 3 Jan 2013 11:09:11 -0800
From: Eric Johnson <ericj@mips.com>
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Subject: Re: [Qemu-devel] [PATCH] linux-user: fix mips 32-on-64 prealloc case
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To: Richard Henderson <rth@twiddle.net>
Cc: Peter Maydell <peter.maydell@linaro.org>, Riku Voipio <riku.voipio@linaro.org>, Michael Tokarev <mjt@tls.msk.ru>, Alexander Graf <agraf@suse.de>, qemu-devel qemu-devel <qemu-devel@nongnu.org>, Aurelien Jarno <aurelien@aurel32.net>

On 01/03/2013 10:50 AM, Richard Henderson wrote:
> On 01/03/2013 10:39 AM, Eric Johnson wrote:
>> While making this change please keep in mind that newer MIPS32
>> processors allow more than 31 bits of user address space (up to 3.5
>> GiB) if they have Enhanced Virtual Address support.
> Interesting.
>
> Well, would you be able to help figure out exactly what's going on in:
>
>    http://lists.gnu.org/archive/html/qemu-devel/2012-12/msg03233.html
>
> and the thread leading up to it?
>
> Now, I don't *know* that this is an emulation failure -- the linux-user-test
> binary certainly isn't aware of enhanced virtual addresses.  So it's
> possible that (older?) binaries can't cope with more than 2GB.
>
> Alternately, it really is a translation problem somewhere...
>
>
> r~

That is correct.  The current test and MIPS32 processors supported by 
QEMU do not support more than 2 GiB of user space.  I didn't mean to 
imply otherwise.

Looking at the MIPS32 processor linux-user on a 64-bit host issue is 
already on my long list of tasks.  Sorry I have not been able to look at 
it yet.

On second thought ignore my EVA comment for now.  We'll worry about that 
when implementing EVA.

Eric