Re: [Qemu-devel] [PATCH] dimm: Correct type of MemoryHotplugState->base

[David Gibson]

On Fri, Jan 22, 2016 at 03:32:52PM +0100, Igor Mammedov wrote:
> On Fri, 22 Jan 2016 15:21:05 +0100
> Paolo Bonzini <address@hidden> wrote:
> 
> > On 22/01/2016 11:02, Igor Mammedov wrote:
> > > On Thu, 21 Jan 2016 12:37:51 +1100
> > > David Gibson <address@hidden> wrote:
> > >   
> > >> The 'base' field of MemoryHotplugState is ram_addr_t, which indicates 
> > >> that
> > >> it exists in the abstract address space of RAM regions.
> > >>
> > >> However, the actual usage of this field indicates that it is a concrete
> > >> physical address (it's passed as an offset to 
> > >> memory_region_add_subgregion
> > >> for example).
> > >>
> > >> So, correct its type to 'hwaddr'.
> > >>
> > >> Signed-off-by: David Gibson <address@hidden>
> > >> ---
> > >>  include/hw/mem/pc-dimm.h | 2 +-
> > >>  1 file changed, 1 insertion(+), 1 deletion(-)
> > >>
> > >> diff --git a/include/hw/mem/pc-dimm.h b/include/hw/mem/pc-dimm.h
> > >> index d83bf30..218dfb0 100644
> > >> --- a/include/hw/mem/pc-dimm.h
> > >> +++ b/include/hw/mem/pc-dimm.h
> > >> @@ -77,7 +77,7 @@ typedef struct PCDIMMDeviceClass {
> > >>   * @mr: hotplug memory address space container
> > >>   */
> > >>  typedef struct MemoryHotplugState {
> > >> -    ram_addr_t base;
> > >> +    hwaddr base;
> > >>      MemoryRegion mr;
> > >>  } MemoryHotplugState;
> > >>    
> > > 
> > > I agree with this fix but that's not the only place where
> > > ram_addr_t needs to be replaced with hwaddr.
> > > For example type of MachineState.[max]ram_size fields needs
> > > to be changed as well. Because QEMU builds without CONFIG_XEN_BACKEND
> > > on 32-bit hosts are broken since ram_addr_t is 32-bits there
> > > while some targets assume and use it as 64-bit one.  
> > 
> > But on a 32-bit system without CONFIG_XEN_BACKEND you cannot allocate
> > more than 4G anyway, so the choice of ram_addr_t is understandable in
> > that case.
> QEMU build will probably fail with above config but if it succeeds
> then maxmem will be silently truncated.
> 
> > 
> > On the other hand, on a 32-bit system without CONFIG_XEN_BACKEND you
> > definitely can place 128M of hot plugged memory between say 4096MB and
> > 4224MB.
> True.
> 
> Anyway for this patch
> Reviewed-by: Igor Mammedov <address@hidden>

Who needs to take this patch?  I'm not sure if I need to do anything
further to push it forwards.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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