Re: IA64 memory

From: Bukie Mabayoje <bukiemab_at_gte.net>
Date: 2005-02-21 04:29:06
Vaibhav Sharma wrote:

> hi,
> Thanks for all the help..
>
> I am actually very new to EFI.
>
> I had studied the EFI provided memory map...(Efiloader data,
> Eficonventional memory etc)..
> But I had one doubt...
> The memory map from efi is also defined for locations more than that
> which is available (I had 6GB of RAM on the machine, but the memory
> map covered addresses more than 6GB). I could not understand why it
> does so...

Post the memmap output.    ----> Don't forget to convert it from unicode to ascii

>
> These addresses contained efi memory types as in the "actual"
> available memory (< 6GB) like "efiConventionaMemory"and type
> "MemoryIOPortSpace" in the end.
>
> It would be great if I could get some documentation on how this memory
> map is created

Read the Memory Allocation Service. The chapter # is different  between the spec versions.

> and why the memory map is supplied to the kernel for
> address ranges more than that existing in physical memory. Also the
> kernel will be using the "WB" type of memory only, and in the dump of
> efi memory map, i found that the these zones had "WB" type. Are these
> zones also used by the kernel and if not, for what purpose these zones
> are.

There are various reason why an OS maps a memory region with a given attribute and that is beyond the scope of this mail. It is easier to talk about specific attributes.
Also read ExitBootServices(), it will explain the hand over of EFI memory map to the OS. On exit of ExitBootServices the OS owns all available (EfiConventionalMemory)  memory and a few others it can reclaim.. At this point it can do as it see fit with ONLY the memory its owns.

>
> TIA
> ---
> vaibhav
> On Sun, 6 Feb 2005 11:39:02 +0530, Vaibhav Sharma <vaibhav.sh@gmail.com> wrote:
> > hi,
> >
> > Thanks for the reply again.
> >
> > Actually, my task requires me to modify the available physical memory.
> > I was trying to locate the place where the kernel stores the amount of
> > memory. Is this value stored in ia64_boot_param structure..?..If I am
> > wrong, please so tell, and whether that there is some other place
> > where this value is stored?
> >
> > I have not tried the elilo sources to locate the structure.
> > I tried to locate the structure in the kernel sources, but i couldn't
> > find the place where this structure is initialized, or where the
> > particular elements of the data structure are asigned values. As you
> > told, the  boot param structure is set up by elilo. I wanted to know
> > that when the EFI comes into play..
> > Is it that elilo reads the values from EFI?
> > Also, i wanted to ask that whether EFI is stored in memory, so that it
> > is accessible to the kernel sources?
> >
> > Please do reply...
> > ---
> > Vaibhav
> >
> > On Thu, 3 Feb 2005 18:31:36 -0800, David Mosberger
> > <davidm@napali.hpl.hp.com> wrote:
> > > >>>>> On Thu, 3 Feb 2005 12:33:40 +0530, Vaibhav Sharma <vaibhav.sh@gmail.com> said:
> > >
> > >  Vaibhav> Hi, Thanks a lot for a quick response, I appreciate.  If
> > >  Vaibhav> you could only help me out a little more $,1s&(B.
> > >
> > >  Vaibhav> See, I need to change some of the boot parameters as
> > >  Vaibhav> read/seen by the kernel. Once these parameters have been
> > >  Vaibhav> setup by elilo, the Kernel must read it from these
> > >  Vaibhav> predefined areas in memory, into some of its variables. I
> > >  Vaibhav> need to understand where this reading part happens in the
> > >  Vaibhav> kernel. This is where I want to modify the resources, for
> > >  Vaibhav> future use by the kernel !! I don't want to touch the elilo
> > >  Vaibhav> source, only the kernel.
> > >
> > > Why not grep the sources for ia64_boot_param?
> > >
> > >        --david
> > >
> > > -
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> > >
> >
> > --
> > Vaibhav Sharma.
> >
> -
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Received on Sun Feb 20 12:13:28 2005

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