[Qemu-devel] Re: [PATCH 2/6] Use correct types to enable > 2G support (v2)

[Izik Eidus <izike@qumranet.com>]

On Sun, 2008-02-03 at 19:56 -0600, Anthony Liguori wrote:
> Hi Izik,

Hi

> 
> Anthony Liguori wrote:
> > Index: qemu/cpu-all.h
> > ===================================================================
> > --- qemu.orig/cpu-all.h	2008-02-01 15:24:45.000000000 -0600
> > +++ qemu/cpu-all.h	2008-02-01 15:28:48.000000000 -0600
> > @@ -695,7 +695,7 @@
> >  
> >  /* page related stuff */
> >  
> > -#define TARGET_PAGE_SIZE (1 << TARGET_PAGE_BITS)
> > +#define TARGET_PAGE_SIZE (1ul << TARGET_PAGE_BITS)
> >  #define TARGET_PAGE_MASK ~(TARGET_PAGE_SIZE - 1)
> >  #define TARGET_PAGE_ALIGN(addr) (((addr) + TARGET_PAGE_SIZE - 1) & TARGET_PAGE_MASK
> 
> Do you recall what this change fixed?  As Paul pointed out in IRC, using 
> the host type here doesn't really fix the problem (target_ulong would be 
> more appropriate).  However, we're both curious what problem it's 
> actually fixing since sign extending the int should just work.

ok the commit say:

   kvm: qemu: change the type of the various page masks to unsigned long
    
   prevents truncation with >=4GB of guest physical memory


as far as i remember it was used to address something with
cpu_physical_memory_rw() probably related to &TARGET_PAGE_SIZE
or ~TARGET_PAGE_SIZE,

the fact is that i dont know if it ever fixed anything