On 11 November 2011 15:59, Alexander Graf <ag...@suse.de> wrote: > This is the machine init function. The s390 virtio machine's ram layout is > defined to be exactly as I posted in the previous post. So there won't be > any ram starts at != 0 or multiple mappings :).
That's the layout of the RAM in target_phys_addr_t space. The layout of the ram in ram_addr_t space is not guaranteed to be the same, it just happens to be in this case. >>> On 10.11.2011, at 02:36, Peter Maydell wrote: >> In summary, either: >> (1) you need to ask the memory region for its ram_addr_t >> [there doesn't seem to be an API for this at the moment], >> do arithmetic on ram_addr_t's and use qemu_get_ram_ptr() to >> get a host pointer corresponding to that ram_addr_t >> or (2) you need to do your arithmetic in target_phys_addr_t's >> (and then you can say your RAM starts at physaddr 0, which >> is guaranteed, rather than at ram_addr_t 0, which isn't) >> and use cpu_physical_memory_map/unmap(). > > I still don't get it. What I want is: > > for (i = ram_size; i < my_ram_size; i++) > stb_phys(env, i, 0); > > cpu_physical_memory_map gives me a pointer to the memory region between > ram_size and my_ram_size. I memset(0) it. I don't see how I could possibly > have different offsets anywhere. If cpu_physical_memory_map would take > anything different than physical address, a lot of assumptions in QEMU code > would break. Yes, so that's option (2) and you need to be using a target_phys_addr_t. -- PMM
