Re: [RFC] q800: fix I/O memory map

[Philippe Mathieu-Daudé]

On 11/2/19 7:10 PM, Laurent Vivier wrote:
> Paolo,
>
> the RFC was mainly for you:
>
> Is this the good way to replicate 256 times a memory chunk containing a
> bunch of different MMIO spaces?

I asked Richard about this and he said this is OK because this is
the FlatView memory tree. It is then optimized in AddressSpace
(see memory_region_transaction_commit). What matters in term of
performance are the AddressSpaces.

> ...
> > +    /*
> > +     * Memory from VIA_BASE to VIA_BASE + 0x40000 is repeated
> > +     * from VIA_BASE + 0x40000 to VIA_BASE + 0x4000000
> > +     */
> > +    for (i = 1; i < 256; i++) {
> > +        MemoryRegion *io = g_malloc(sizeof(*io));
> > +        char *name = g_strdup_printf("mac_m68k.io[%d]", i);
> > +
> > +        memory_region_init_alias(io, NULL, name, get_system_memory(),
> > +                                 VIA_BASE, 0x40000);
> > +        memory_region_add_subregion(get_system_memory(),
> > +                                    VIA_BASE + i * 0x40000, io);
> > +        g_free(name);
> > +    }
> > +
> ...
> Thanks,
> Laurent