Re: [Qemu-devel] Re: [PATCH] Make page_find() return 0 for too-large addresses

[Anthony Liguori]

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