Messages in this thread |  | | | Subject | Re: [RFC][PATCH] Randomize kernel base address on boot | | From | Dan Rosenberg <> | | Date | Tue, 24 May 2011 19:34:49 -0400 |
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On Tue, 2011-05-24 at 16:07 -0700, H. Peter Anvin wrote: > On 05/24/2011 04:04 PM, Dan Rosenberg wrote: > > > >> 2. Not introduce a performance regression (we avoid locating in the > >> bottom 16 MiB for performance reasons, except on very small systems); > > > > I altered the boot code so that it uses CONFIG_PHYSICAL_START, which > > defaults to 16 MiB, as a lower bound on location. So nothing will ever > > get loaded below there, and I still can take advantage of higher > > alignment granularity. Are there other problems I'm not anticipating? > > > > Please look at the discussion as to what led us to do things this way. >
Would you be able to point me to said discussion? The only thing I can find is this:
http://marc.info/?l=linux-kernel&m=124173552516435&w=2
This set PHYSICAL_START at 16 MB and alignment at 2/4 MB. Then, three days later, this was committed:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ceefccc93932b920a8ec6f35f596db05202a12fe
This sets the alignment to 16 MB, with the only justification being that relocatable kernels also need to start above 16 MB.
Thanks, Dan
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