Hi, On Wed, Feb 21, 2018 at 08:06:10AM +0100, Christophe LEROY wrote: > > > Le 20/02/2018 à 17:14, Jonathan Neuschäfer a écrit : > > This patchset adds support for DISCONTIGMEM on 32-bit PowerPC. This is > > required to properly support the Nintendo Wii's memory layout, in which > > there are two blocks of RAM and MMIO in the middle. > > > > Previously, this memory layout was handled by code that joins the two > > RAM blocks into one, reserves the MMIO hole, and permits allocations of > > reserved memory in ioremap. This hack didn't work with resource-based > > allocation (as used for example in the GPIO driver for Wii[1]), however. > > > > After this patchset, users of the Wii can either select CONFIG_FLATMEM > > to get the old behaviour, or CONFIG_DISCONTIGMEM to get the new > > behaviour. > > My question might me stupid, as I don't know PCC64 in deep, but when looking > at page_is_ram() in arch/powerpc/mm/mem.c, I have the feeling the PPC64 > implements ram by blocks. Isn't it what you are trying to achieve ? Wouldn't > it be feasible to map to what's done in PPC64 for PPC32 ? Using page_is_ram in __ioremap_caller and the same memblock-based approach that's used on PPC64 on PPC32 *should* work, but I think due to the following line in initmem_init, it won't: memblock_set_node(0, (phys_addr_t)ULLONG_MAX, &memblock.memory, 0); Thanks, Jonathan Neuschäfer
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