Am 23.07.2013 um 23:19 schrieb Scott Wood <scottw...@freescale.com>:
> On 07/23/2013 04:15:59 PM, Alexander Graf wrote: >> On 23.07.2013, at 21:38, Scott Wood wrote: >> > On 07/22/2013 10:28:17 AM, Alexander Graf wrote: >> >> Today we generate the device tree once on machine initialization and then >> >> store the finalized blob in memory to reload it on reset. >> >> This is bad for 2 reasons. First we potentially waste a bunch of RAM for >> >> no >> >> good reason, as we have all information required to regenerate the device >> >> tree available anyways. >> >> The second reason is even more important. On machine init when we generate >> >> the device tree for the first time, we don't have all of the devices fully >> >> initialized yet. But the device tree needs to potentially walk devices to >> >> put information about them into the device tree. >> > >> > If you can't produce the entire device tree at init time, how can you >> > calculate its size with a dry run? >> > >> > Device trees are generally pretty small; couldn't we just set a maximum >> > size and allocate that much space? >> It's what we do, unless we load it from the disk. In that case we take the >> fdt size from disk. > > So why do we need the dry run stuff? Because dumpdtb otherwise generates a halfway complete dtb on the first dry pass as device realization is yet incomplete :). Alex > > -SCott
