On Fri, Oct 25, 2013 at 12:55:36AM +0100, Paolo Bonzini wrote: > > + if (hpagesize == (1<<30)) { > > + unsigned long holesize = 0x100000000ULL - below_4g_mem_size; > > + > > + memory_region_init_alias(ram_above_4g, NULL, "ram-above-4g", > > ram, > > + 0x100000000ULL, > > + above_4g_mem_size - holesize); > > + memory_region_add_subregion(system_memory, 0x100000000ULL, > > + ram_above_4g); > > + > > + ram_above_4g_piecetwo = > > g_malloc(sizeof(*ram_above_4g_piecetwo)); > > + memory_region_init_alias(ram_above_4g_piecetwo, NULL, > > + "ram-above-4g-piecetwo", ram, > > + 0x100000000ULL - holesize, holesize); > > + memory_region_add_subregion(system_memory, > > + 0x100000000ULL + > > + above_4g_mem_size - holesize, > > + ram_above_4g_piecetwo); > > Why break it in two? You can just allocate extra holesize bytes in the > "ram" MemoryRegion, and not map the part that corresponds to > [0x100000000ULL - holesize, 0x100000000ULL).
- If the "ram" MemoryRegion is backed with 1GB hugepages, you might not want to allocate extra holesize bytes (which might require an entire 1GB page). - 1GB backed RAM can be mapped with 2MB pages. > Also, as Peter said this cannot depend on host considerations. Just do > it unconditionally, but only for new machine types (pc-1.8 and q35-1.8, > since unfortunately we're too close to hard freeze). Why the description of memory subregions and aliases are part of machine types?