Messages in this thread | | | Date | Tue, 24 May 2011 16:36:39 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [RFC][PATCH] Randomize kernel base address on boot |
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On 05/24/2011 04:34 PM, Dan Rosenberg wrote: > 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. >
I think those patches came after the discussion were already over. I'll try to look for it.
-hpa
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