Messages in this thread | | | Date | Thu, 10 Jan 2008 14:15:25 -0800 (PST) | From | Linus Torvalds <> | Subject | RE: [patch 02/11] PAT x86: Map only usable memory in x86_64 identity map and kernel text |
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On Thu, 10 Jan 2008, Pallipadi, Venkatesh wrote: > > Yes. I had those pages not mapped at all earlier. The reason I switched > to zero page is to continue support cases like: > BIOS-e820: 0000000000000000 - 000000000009cc00 (usable) > BIOS-e820: 000000000009cc00 - 00000000000a0000 (reserved) > BIOS-e820: 00000000000cc000 - 00000000000d0000 (reserved) > BIOS-e820: 00000000000e4000 - 0000000000100000 (reserved) > BIOS-e820: 0000000000100000 - 00000000cff60000 (usable) > > In this case if some one does a dd of /dev/mem before they can read the > contents of usable memory in 0x100000-0xcff60000 range.
Well, I think that /dev/mem should simply give them the right info. That's what people use /dev/mem for - doing things like reading BIOS images etc.
So returning *either* a zero page *or* stopping at the first hole is both equally wrong.
Linus
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