Messages in this thread | | | Subject | Re: proper way to reserve a chunk of memory at the top of the kernel? | From | Benjamin Herrenschmidt <> | Date | Mon, 20 Jul 2009 11:54:05 +1000 |
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On Tue, 2009-07-14 at 15:18 -0600, Chris Friesen wrote: > I have a powerpc board with 512BM of memory. The BIOS has a chunk of > memory at the top end of physical memory which it does not zero out over > a reboot. > > What's the proper way to tell linux that this chunk of physical memory > should be ignored (so that we can access it later without worrying that > Linux will try to allocate it)? Should I be calling > > lmb_reserve(lmb_end_of_DRAM() - size, size); > > in early_reserve_mem() or is there a better mechanism?
The device-tree blob contains a special "reserve map" in the header, which automatically turns into calls to lmb_reserve() early during boot, so putting your special region in that map should be the right way to do what you want without special code.
> For comparison, in an older kernel this was done in set_phys_avail(), by > calling mem_pieces_remove(&phys_avail, total_lowmem - size, size, 1);
Cheers, Ben.
> Thanks, > > Chris > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev
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