On Tue, 15 Jan 2019 17:07:38 PST (-0800), guoren@xxxxxxxxxx wrote:
Hi Christoph, I use PFN_DOWN() every where as possible and seems it's a habit problem. So let risc-v maintainer to choose "PFN_DOW()" or ">> PAGE_SHIFT". Also the same with "end_of_DRAM & max_low_pfn".
PFN_DOWN makes sense to me, as that's what we're trying to do here (round a physical address down to page frame number). Am a I misunderstanding something?
Best Regards Guo Ren On Tue, Jan 15, 2019 at 08:12:54AM -0800, Christoph Hellwig wrote:On Wed, Jan 16, 2019 at 12:10:00AM +0800, Guo Ren wrote: > > > set_max_mapnr(PFN_DOWN(mem_size)); > > > - max_low_pfn = memblock_end_of_DRAM(); > > > + max_low_pfn = PFN_DOWN(memblock_end_of_DRAM()); > > > > I know it is used just above, but can we please just switch this > > code to use >> PAGE_SHIFT instead of PFN_DOWN, which just horribly > > obsfucates what is going on? > ??? > #define PFN_DOWN(x) ((x) >> PAGE_SHIFT) > > phys_addr_t __init_memblock memblock_end_of_DRAM(void) > { > int idx = memblock.memory.cnt - 1; > > return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size); > } > > What's the problem? PFN_DOWN() couldn't be used with function call? PFN_DOWN gives you the correct result. But I think it actually drastically reduces readability over just opencoding it. > My patch just want to point out that max_low_pfn is PFN not size. In fact > there is no error for running without my patch :P No, I think your patch is correct. I just wonder if we could make the code easier to read.
