lkml.org 
[lkml]   [2009]   [Jul]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: proper way to reserve a chunk of memory at the top of the kernel?
From
Date
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



\
 
 \ /
  Last update: 2009-07-20 03:57    [W:0.203 / U:0.020 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site