On Mon, 20 Nov 2017, Guenter Roeck wrote: > On Mon, Nov 20, 2017 at 07:28:21PM -0500, Nicolas Pitre wrote: > > On Mon, 20 Nov 2017, Guenter Roeck wrote: > > > > > bdata->node_min_pfn=60000 PFN_PHYS(bdata->node_min_pfn)=c0000000 start_off=536000 region=c0536000 > > > > If PFN_PHYS(bdata->node_min_pfn)=c0000000 and > > region=c0536000 that means phys_to_virt() is a no-op. > > > No, it is |= 0x80000000 Then the bootmem registration looks very fishy. If you have: > I think the problem is the 0x60000 in bdata->node_min_pfn. It is shifted > left by PFN_PHYS, making it 0xc0000000, which in my understanding is > a virtual address. Exact. #define __pa(x) ((unsigned long)(x) & 0x7fffffff) #define __va(x) ((void *)((unsigned long)(x) | 0x80000000)) With that, the only possible physical address range you may have is 0x40000000 - 0x7fffffff, and it better start at 0x40000000. If that's not where your RAM is then something is wrong. This is in fact a very bad idea to define __va() and __pa() using bitwise operations as this hides mistakes like defining physical RAM address at 0xc0000000. Instead, it should look like: #define __pa(x) ((unsigned long)(x) - 0x80000000) #define __va(x) ((void *)((unsigned long)(x) + 0x80000000)) This way, bad physical RAM address definitions will be caught immediately. > That doesn't seem to be easy to fix. It seems there is a mixup of physical > and virtual addresses in the architecture. Well... I don't think there is much else to say other than this needs fixing. Nicolas -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
