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Date: Fri, 12 Sep 2008 16:27:30 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] Re: [PATCH] Make page_find() return 0 for too-large
	addresses
References: <20080912185856.GM3982@blackpad> <48CAC809.5000901@codemonkey.ws>
	<20080912201406.GA10147@blackpad> <20080912204404.GB10147@blackpad>
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To: Eduardo Habkost <ehabkost@redhat.com>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, gcosta@redhat.com

Eduardo Habkost wrote:
> On Fri, Sep 12, 2008 at 05:14:06PM -0300, Eduardo Habkost wrote:
>   
>> On Fri, Sep 12, 2008 at 02:50:33PM -0500, Anthony Liguori wrote:
>>     
>>> Eduardo Habkost wrote:
>>>       
>>>> On some cases, such as under KVM, tb_invalidate_phys_page_range()
>>>> may be called for large addresses, when qemu is configured to more than
>>>> 4GB of RAM.
>>>>
>>>> On these cases, qemu was crashing because it was using an index too
>>>> large for l1_map[], that supports only 32-bit addresses when compiling
>>>> without CONFIG_USER_ONLY.
>>>>   
>>>>         
> <snip>
>   

So... are you building with kqemu enabled?  If so, 
TARGET_PHYS_ADDR_SPACE_BITS will be 32.  So I don't think this sort of 
work-around is correct.  A better solution would be to validate ram_size 
against TARGET_PHYS_ADDR_SPACE_BITS.

To put it another way, if you have kqemu enabled (at build time), you 
cannot use > ~4GB of memory for the guest.

Regards,

Anthony Liguori