Re: [Qemu-devel] [PULL 0/3] 128-bit support for the memory API

[David Gibson <dwg@au1.ibm.com>]

On Mon, Oct 31, 2011 at 11:05:47AM -0500, Anthony Liguori wrote:
> On 10/30/2011 09:02 AM, Avi Kivity wrote:
> >This somewhat controversial patchset converts internal arithmetic in the
> >memory API to 128 bits.
> 
> Given the level of controversy, what do you think about deferring
> this to 1.1?

If it's deferred then one of my rearrangements for the arithmetic must
go in instead.  These patches fix real bugs, that bite us on pseries.
It's not the only way to fix those bugs, and probably not even my
personally preferred way to fix them, but they need to be fixed
_somehow_ for 1.0.


> 
> Regards,
> 
> Anthony Liguori
> 
> >
> >It has been argued that with careful coding we can make 64-bit work as
> >well.  I don't think this is true in general - a memory router can adjust
> >addresses either forwards or backwards, and some buses (PCIe) need the
> >full 64-bit space - though it's probably the case for all the configurations
> >we support today.  Regardless, the need for careful coding means subtle bugs,
> >which I don't want in a core API that is driven by guest supplied values.
> >
> >Avi Kivity (3):
> >   Add support for 128-bit arithmetic
> >   memory: use 128-bit integers for sizes and intermediates
> >   Adjust system and pci address spaces to full 64-bit
> >
> >  exec.c          |    2 +-
> >  hw/pc_piix.c    |    2 +-
> >  hw/pci_bridge.c |    2 +-
> >  int128.h        |  116 ++++++++++++++++++++++++++++++++
> >  memory.c        |  196 ++++++++++++++++++++++++++++++++----------------------
> >  memory.h        |    3 +-
> >  6 files changed, 237 insertions(+), 84 deletions(-)
> >  create mode 100644 int128.h
> >
> 

-- 
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_!
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