Messages in this thread | | | Date | Tue, 3 Jan 2017 16:31:37 +0800 | From | Baoquan He <> | Subject | Re: [PATCH] x86: fix kaslr and memmap collision |
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Hi Dan,
On 11/22/16 at 09:26am, Dan Williams wrote: > [ replying for Dave since he's offline today and tomorrow ] > > On Tue, Nov 22, 2016 at 12:47 AM, Ingo Molnar <mingo@kernel.org> wrote: > > > > * Dave Jiang <dave.jiang@intel.com> wrote: > > > >> CONFIG_RANDOMIZE_BASE relocates the kernel to a random base address. > >> However it does not take into account the memmap= parameter passed in from > >> the kernel commandline. > > > > memmap= parameters are often used as a list. > > > >> [...] This results in the kernel sometimes being put in the middle of the user > >> memmap. [...] > > > > What does this mean? If memmap= is used to re-define the memory map then the > > kernel getting in the middle of a RAM area is what we want, isn't it? What we > > don't want is for the kernel to get into reserved areas, right? > > Right, this is about teaching kaslr to not land the kernel in newly > defined reserved regions that were not marked reserved in the initial > e820 map from platform firmware.
If only tell kaslr to not land kernel in newly defined reserved regions, memory added by "memmap=nn[KMG]@ss[KMG]" should not be avoided since it's usable memory. Kernel randomized into this region is also what we want. Not sure if I understand it right.
Thanks Baoquan
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