On 12/02/2011 04:49 PM, Peter Maydell wrote: > Hi; I was working on a refactoring of the ARM 11MPCore/A9MP private > peripherals and encountered something odd. Rather than having a single > large mmio region, I tried splitting into several regions, like this: > > memory_region_init(&s->container, "a9mp-priv-container", 0x2000); > memory_region_init_io(&s->scu_iomem, &a9_scu_ops, s, "a9mp-scu", 0x100); > memory_region_init_io(&s->gic_cpu_iomem, &a9_gic_cpu_ops, s, > "a9mp-gic-cpu", 0x100); > memory_region_init_io(&s->ptimer_iomem, &a9_ptimer_ops, s, > "a9mp-ptimer", 0x100); > memory_region_add_subregion(&s->container, 0, &s->scu_iomem); > memory_region_add_subregion(&s->container, 0x100, &s->gic_cpu_iomem); > memory_region_add_subregion(&s->container, 0x600, &s->ptimer_iomem); > memory_region_add_subregion(&s->container, 0x1000, &s->gic.iomem); > sysbus_init_mmio_region(dev, &s->container);
Good practice IMO, will become more important when we introduce a Register class. > However what I found is that the addresses passed to the read/write > functions aren't what I would expect. For instance if the board > maps the container at address 0x1e000000, then a read from 0x1e000100 > goes to the functions given by a9_gic_cpu_ops, as it should. However, > the offset parameter that the read function is passed is not 0x0 > (offset from the start of the a9mp-gic-cpu region) but 0x100 (offset > from the start of the page, I think). > > Is this expected behaviour? I certainly wasn't expecting it... A while ago this was the behaviour across the board. Then 8da3ff1809747 changed addresses to be relative, but apparently missed the subpage case. > I looked through the code that's getting called for reads, and > it looks to me like exec.c:subpage_readlen() is causing this. > We look up the subpage_t based on the address within the page, > but we don't then adjust the address we pass to io_mem_read > (except by region_offset, which I take from the comment at the > top of cpu_register_physical_memory_log() to be for something > else.) > I think you can use subpage_t's region_offset array for this (adding into it, of course, so the original value remains). -- error compiling committee.c: too many arguments to function
