reserving memory using OF rsvmap feature?

Joakim Tjernlund joakim.tjernlund at
Wed Jun 13 03:20:18 EST 2012

"Jenkins, Clive" <Clive.Jenkins at> wrote on 2012/06/12 17:48:15:
> > Is it possible to reserve some memory using OF rsvmap such that Linux
> > will not touch this area at all? Think of is as warm start stash area
> > were one could store data which should survive a reboot.
> Yes, I guess it should be possible, but you need to take care where you
> place this block so it does not get overwritten during the boot process.
> This depends on how your bootloader is set up to place images in memory,
> decompress them etc.
> I don't know about OF, but in U-Boot use the function fdt_add_mem_rsv()
> in file
> // Reserve the memory location of the framebuffer + descriptor page.
> if (fdt_add_mem_rsv(working_fdt, fbinfo->smem_start,
>                     (fbinfo->smem_len + 0x1FFF) & 0xFFFFF000))
>    printf("ERROR: could not reserve FB memory in device tree\n");
> In my powerpc_e500v2 systems this block is located at 64MiB
> (0x04000000).

Thanks, this was what I was looking at too. I plan to use u-boots PRAM feature
and reserve memory at the end of RAM.


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