>-----Original Message----- >From: Linus Torvalds [mailto:[EMAIL PROTECTED] >Sent: Thursday, January 10, 2008 2:15 PM >To: Pallipadi, Venkatesh >Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED]; >[EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED]; >[EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED]; >[EMAIL PROTECTED]; Barnes, Jesse; [EMAIL PROTECTED]; >[email protected]; Siddha, Suresh B >Subject: RE: [patch 02/11] PAT x86: Map only usable memory in >x86_64 identity map and kernel text > > > >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. >
I was not fully clear in my earlier email. Mapping /dev/mem would still work with our changes. As they go through proper map interface. It is the dd of dev mem which does the read that has the problem. I was wondering of apps using dd. Thanks, Venki -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
