Re: [Xen-devel] [PATCH V2 3/4] xen/arm: Add support for Broadcom 7445D0 A15 platform.

[Jonathan Fraser <jfraser@xxxxxxxxxxxx>]

On Fri, 2014-10-03 at 16:22 +0100, Ian Campbell wrote:
> On Fri, 2014-10-03 at 15:15 +0000, Jonathan Fraser wrote:
> > On Fri, 2014-10-03 at 11:44 +0100, Julien Grall wrote:
> > > Hello Jon,
> > > 
> > > On 02/10/2014 23:16, Jon Fraser wrote:
> > > > This code supports the Broadcom 7445D0 32-bit A15 based platform.
> > > 
> > > While this patch has been acked and applied. Did you check that the (by 
> > > default mapped 0xb0000000-0xb0020000) doesn't overlap to the RAM or 
> > > another device on your platform?
> > > 
> > > Regards,
> > > 
> > 
> > I had a question about that.  This is a guest physical address, not the
> > machine physical address?
> 
> It's guest physical but dom0 is mapped 1:1 so that is somewhat the same
> as machine physical in this instance.
> 
> >   What are the restrictions?
> 
> It just needs to be a hole in the address space which isn't used for
> anything else, so not RAM and not MMIO.
> 
> Since dom0 is 1:1 mapped for MMIO this means a hole in the machine
> address map, or as a last resort an address used by something which
> isn't given to dom0.
> 
> In 4.6 we are going to sort out a way of finding these addresses
> automatically, so the suckitude of having to figure one out will go
> away...
> 
> > On our current platforms, memory always starts at 0 and we currently
> > support between 1 and 6 GB.  There's always a 1GB hole at 0xc0000000.
> 
> I suppose this is an MMIO hole? Any free space in thatregion would do.

Yes, it has MMIO, flash, SROM, SRAM, PCI and some empty space.
> 
> > However in the future, memory will start at 0x40000000 and extend
> > contiguously past 32-bit space for up to 4GB of memory, then segmented
> > in 36-bit address space.
> 
> In this case I guess the MMIO has moved to 0...0x40000000? Might need to
> move the gnttab then too, or maybe we'll have fixed this in the core by
> then (fingers crossed!)
> 


Yes, everything that was at 0xc... moved to 0x0, starting with the boot
vector and flash.  This will also be the map for 64-bit systems.
These new parts will have new part numbers and DTBs.

> > I haven't tried a guest with much more than 1GB of memory, but will
> > try that today.
> > 
> > Thanks,
> > Jon
> > 
> > 
> 
> 

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