On 02/09/2012 04:23 PM, Jan Kiszka wrote:
> On 2012-02-09 10:32, Avi Kivity wrote:
> > On 02/09/2012 10:35 AM, Jan Kiszka wrote:
> >> Avi,
> >>
> >> Before I forget:
> >>
> >> On 2012-02-05 13:39, Jan Kiszka wrote:
> >>> +static void vapic_map_rom_writable(VAPICROMState *s)
> >>> +{
> >>> + target_phys_addr_t rom_paddr = s->rom_state_paddr & ROM_BLOCK_MASK;
> >>> + MemoryRegionSection section;
> >>> + MemoryRegion *as;
> >>> + size_t rom_size;
> >>> + uint8_t *ram;
> >>> +
> >>> + as = sysbus_address_space(&s->busdev);
> >>> +
> >>> + if (s->rom_mapped_writable) {
> >>> + memory_region_del_subregion(as, &s->rom);
> >>> + memory_region_destroy(&s->rom);
> >>> + }
> >>> +
> >>> + /* grab RAM memory region (region @rom_paddr may still be pc.rom) */
> >>> + section = memory_region_find(as, 0, 1);
> >>> +
> >>> + /* read ROM size from RAM region */
> >>> + ram = memory_region_get_ram_ptr(section.mr);
> >>> + rom_size = ram[rom_paddr + 2] * ROM_BLOCK_SIZE;
> >>> + s->rom_size = rom_size;
> >>> +
> >>> + /* FIXME: round up as everything underneath would fall apart
> >>> otherwise
> >>> + * (subpages are broken) */
> >>> + rom_size = TARGET_PAGE_ALIGN(rom_size);
> >>
> >> Removing this alignment triggers an interesting bug in the memory layer.
> >> Haven't understood the details yet. Is subpage support supposed to work?
> >>
> >>
> >
> > There are plenty of restrictions wrt page size in the memory API. Some
> > will be removed, some are enforced by hardware (for example the low bits
> > of the guest address and host address must match).
> >
> > Subpage of course works, but it can't be direct mapped.
> >
>
> Does this mean you can't use them with RAM backing? Should probably be
> documented and caught gracefully in that case.
Since a few monthss ago, you can (56384e8b). But it will be handled as
mmio, of course.
--
error compiling committee.c: too many arguments to function
