On Tuesday 15 December 2015 10:33:25 Pali Rohár wrote: > On Monday 30 November 2015 11:09:42 Nicolas Pitre wrote: > > On Mon, 30 Nov 2015, Pali Rohár wrote: > > > On Monday 30 November 2015 07:23:53 Tony Lindgren wrote: > > > > * Pali Rohár <pali.rohar@xxxxxxxxx> [151129 16:16]: > > > > > On Monday 30 November 2015 01:09:17 Nicolas Pitre wrote: > > > > > > On Sun, 29 Nov 2015, Russell King - ARM Linux wrote: > > > In arch/arm/kernel/setup.c is function setup_arch() and it calls: > > > > > > mdesc = setup_machine_fdt(__atags_pointer); > > > if (!mdesc) > > > mdesc = setup_machine_tags(__atags_pointer, __machine_arch_type); > > > > > > So it looks like that on atags address is stored either atags structure > > > or DT structure... so it is truth kernel uncompress code put DT blob to > > > same offset where is expected atags structure? > > > > No. It doesn't put it anywhere. Those functions read DT/ATAGs from the > > passed address. But you know this address won't be the one you want for > > the legacy ATAGs. > > > > What you should do is to add a init_early hook to your mdesc structure > > and retrieve your ATAGs from there directly at PAGE_OFFSET + 0x100. > > > > Now I suspect paging_init() marks the point where the ATAGs will be > > overwritten. To prevent this, you might have to add an additional tweak > > in arm_mm_memblock_reserve() similar to the one already present for > > CONFIG_SA1111. Something like: > > > > memblock_reserve(PHYS_OFFSET, PAGE_SIZE); > > > > And later on you can return that page back to the system. > > > > So am I understand correctly that solution would be to hack > arch/arm/mm/mmu.c to not overwrite page at PHYS_OFFSET? I would think we can just copy the data from PAGE_OFFSET + 0x100 to a some other page from your init_early hook. IIRC you can't use kmalloc there, but memblock_alloc() should work. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
