Re: [Xen-ia64-devel] Question to memory handling for domU

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxxxxxxx>]

Hi Tristan,

Am Donnerstag, 10. August 2006 15:26 schrieb Tristan Gingold:
> Le Jeudi 10 Août 2006 15:13, Dietmar Hahn a écrit :
> > Hi,
> >
> > while I was playing with my mini-os and the memory a short question comes
> > up: What memory info is relevant and where gets the domU kernel loaded
> > within the (for domU) configured memory?
>
> domU kernel is loaded at its physical address (IIRC).  Check the ELF
> header.
>
> > I have 128MB configured for domU.
> > start_info->nr_pages gives me 8192 pages -> 128MB.
>
> Seems correct :-)
>
> > The memory given by the efi (EfiConventionalMemory) is physically between
> > 0x200000 and 0x7ff4000 -> ~2MB are absent.
> > Do I have to take this efi memory only, right? How is the absent memory
> > used?
>
> You have memory between 0 and 0x200000.  The start_info page is not in the
> memmap (IIRC).
OK I understand. Between 0 and 0x200000 are the bootinfo, efi and pal stuff.
Between 0x200000 and 0x7ff4000 is the memory usable for mini-os. This includes 
the kernel code and data.
Now only the area between 0x7ff4000 and 0x8000000 is unclear.
Is 0x200000 a fix address?

>
> > My kernel gets loaded to physically address 0x4000000.
> > That means the kernel text and data are nearly in middle of the memory.
> > May this be?
>
> Linux loads at 64MB to be 64MB aligned!  As a consequence it may use large
> page (64MB) to map itself.
I took some infos from the linux linker script.

>
> > If yes - I have to check the this and split the memory to
> > separate the kernel?
>
> Choose the load address you prefer.
But it has to be between 0x200000 and the end of the configured memory?

>
> Will mini-os run in physical or virtual mode ?  I think you don't need to
> use virtual mode.  This will simplify the code a lot!
Currently I switch to virtual mode in _start.

>
> Tristan.
Thanks.

Dietmar.

-- 
Dietmar Hahn               Telephone: +49 (0) 89 636 40274
Fujitsu Siemens Computers  Telefax:   +49 (0) 89 636 40601
Otto-Hahn-Ring 6           Email:     dietmar.hahn@xxxxxxxxxxxxxxxxxxx
81739 München, Germany     Internet:  http://www.fujitsu-siemens.com

_______________________________________________
Xen-ia64-devel mailing list
Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-ia64-devel