On Mon, Feb 13, 2017 at 12:17:00PM +0000, Will Deacon wrote: > Adding linux-arm-kernel and devicetree (look for "raw-pfn"), since this > impacts directly on those. > > On Mon, Feb 13, 2017 at 08:02:29PM +0800, zhouxianrong@xxxxxxxxxx wrote: > > From: zhouxianrong <zhouxianrong@xxxxxxxxxx> > > > > just like freeing no-map area's memmap we could free reserved > > area's memmap as well only when user of reserved area indicate > > that we can do this in dts or drivers. that is, user of reserved > > area know how to use the reserved area who could not memblock_free > > or free_reserved_xxx the reserved area and regard the area as raw > > pfn usage. the patch supply a way to users who want to utilize the > > memmap memory corresponding to raw pfn reserved areas as many as > > possible. > > I don't really understand this. Can you point me at a specific use-case, > please? Is CMA involved here? You don't need "dt permission" to free the memmap page array for the regions between memory areas. In fact, adding a DT property for that goes against the "DT describes the hardware not the implementation" requirement, since the memmap page array is a Linux implementation detail. 32-bit ARM has been freeing the memmap page array between memory areas for years since pre-DT days, and continues to do so. See free_unused_memmap(). -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- 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
