Messages in this thread | | | From | "Lyle Coder" <> | Subject | Re: HIGH MEMORY access | Date | Mon, 06 Mar 2000 16:07:38 PST |
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Hello >I don't think (2) is true. All set_fixmap does is to set a PTE into >the kernel map, and PTEs point to physical addresses. The 1GB limitation >is a virtual address mapping limitation, not physical. > set_fixmap relies on __end_of_fixed_addresses which is set to 1GB, correct? The code checks for the address being less than __end_of_fixed_addresses. I beleive this is the highest memory upto which the kernel has page translations.
Please correct me if this is not the case and I can debug further where my code is breaking.
Best Wishes :) Lyle
>From: Andi Kleen <ak@muc.de> >To: Lyle Coder <x_coder@hotmail.com> >CC: ak@muc.de, mingo@chiara.csoma.elte.hu, linux-kernel@vger.rutgers.edu >Subject: Re: HIGH MEMORY access >Date: Sat, 4 Mar 2000 12:30:50 +0100 > >On Sat, Mar 04, 2000 at 03:27:49AM +0100, Lyle Coder wrote: > > Hi, > > The function in question is get_smp_config > > > > 1) No it doesent call set_fixmap > > 2) Even if it did, it wont be able to see > 1GB > >I don't think (2) is true. All set_fixmap does is to set a PTE into >the kernel map, and PTEs point to physical addresses. The 1GB limitation >is a virtual address mapping limitation, not physical. > > >-Andi > > > > > Ingo, am I correct? > > > > Best Wishes, > > Lyle > > > > > > >From: Andi Kleen <ak@muc.de> > > >To: x_coder@hotmail.com (Lyle Coder) > > >CC: linux-kernel@vger.rutgers.edu > > >Subject: Re: HIGH MEMORY access > > >Date: 04 Mar 2000 02:30:07 +0100 > > > > > >x_coder@hotmail.com (Lyle Coder) writes: > > > > > > > Hello All, > > > > I have a question. The BIOS engineers said that the MPS tables will >be > > >in > > > > the highest region of the available RAM... greater than 1 GB if so >much > > > > memory is available. > > > > Further more, the MPS tables will be in a region reported "unusable" >by > > >E820 > > > > (Thats mentioned in the E820 spec). > > > > > > > > So my question is this... > > > > 1) How should we initialize mappings for arbitrary RAM above 1GB so > > >early > > > > on? Should we just set aside a page directory for temporary > > >installation of > > > > translations and provide a clean API to do so? We will need this >for > > >ACPI > > > > and PAE too. > > > > > >Can't you just use set_fixmap, like the current smp code already does >for > > >MP bios tables ? > > > > > > > > >-Andi > > > > > >-- > > >This is like TV. I don't like TV. > > > > ______________________________________________________ > > Get Your Private, Free Email at http://www.hotmail.com > > > >-- >This is like TV. I don't like TV.
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