Benjamin Herrenschmidt wrote: > This patch changes vmemmap to use a different region (region 0xf) of the > address space whose page size can be dynamically configured at boot. > > The problem with the current approach of always using 16M pages is that > it's not well suited to machines that have small amounts of memory such > as small partitions on pseries, or PS3's. > > In fact, on the PS3, failure to allocate the 16M page backing vmmemmap > tends to prevent hotplugging the HV's "additional" memory, thus limiting > the available memory even more, from my experience down to something > like 80M total, which makes it really not very useable. > > The logic used by my match to choose the vmemmap page size is: > > - If 16M pages are available and there's 1G or more RAM at boot, use that > size. > - Else if 64K pages are available, use that > - Else use 4K pages > > I've tested on a POWER6 (16M pages) and on an iSeries POWER3 (4K pages) > and it seems to work fine. > > However, when attempting to test on a PS3, it didn't boot. > > In fact, it doesn't boot without my patch with current upstream.
Yes, this is a know problem I am working on, related to recent changes in bootmem. Errors with: 'sparse_early_usemap_alloc: allocation failed'. I tried > booting 2.6.25 with a ps3_defconfig and that doesn't work neither > (though at least when doing the later, I do get a black screen & no > sync, like of ps3fb failed monitor detection, while with current > upstream, I just get the last kexec messages and nothing happens). This should work. You are the first to report a problem with 2.6.25. Could you double check your build, and if you still have trouble, put your vmlinux somewhere I can get it? > Since the PS3 boot failures are impossible to debug unless your email is > @sony* and you have the special magic tools, I'll let Geoff try the > patch out. OK, I'll try it with the upstream kernel from last week and report within the next day or so. -Geoff _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
