How Can The Starting Address Of An Image In ELF File BeChanged

How Can The Starting Address Of An Image In ELF File BeChanged

[Thamarai Selvan]

Hi all,

I created the elf file of the kernel using "make vmlinux", when i checked
the created system.map i found the the kernel image starting from
0xc0000000. Can any tell where this address is defined or configured? and
how can this be changed to 0x0000000 is it possible?

with regards
Thamarai Selvan.G


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Re: How Can The Starting Address Of An Image In ELF File BeChanged

[Stephen Williams]

Thamarai Selvan Thamarai.Selvan-at-lntinfotech.com |PPC Linux Embedded|
wrote:
> Hi all,
>
> I created the elf file of the kernel using "make vmlinux", when i checked
> the created system.map i found the the kernel image starting from
> 0xc0000000. Can any tell where this address is defined or configured? and
> how can this be changed to 0x0000000 is it possible?

The linux cernel is linked to 0xc0000000, and the entry is really
up there. In fact, the kernel is loaded starting at 0x0, and there
is code at the beginning that turns on address translation so that
it appears at the right place.

In other words, there is nothing for you to change.


--
Steve Williams                "The woods are lovely, dark and deep.
steve at XXXXXXXXXX           But I have promises to keep,
http://www.XXXXXXXXXX         and lines to code before I sleep,
http://www.picturel.com       And lines to code before I sleep."


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Re: How Can The Starting Address Of An Image In ELF File BeChanged

[Thamarai Selvan]

hi

iam still not clear with it
can u guide me 2 some document/link on it or brief it little bit more
why it is linked to that address ?
if it is linked it should be configurable
bcuz iam using vision ice to download my image.
Thanks for your immediate reply

with regards
Thamarai Selvan.G

[ "Stephen Williams" <612dlag102@sneakemail.com> writes: ]

Thamarai Selvan Thamarai.Selvan-at-lntinfotech.com |PPC Linux Embedded| wrote:
>
> I created the elf file of the kernel using "make vmlinux", when i
> checked the created system.map i found the the kernel image starting
> from 0xc0000000. Can any tell where this address is defined or
> configured? and how can this be changed to 0x0000000 is it possible?

The linux cernel is linked to 0xc0000000, and the entry is really up
there. In fact, the kernel is loaded starting at 0x0, and there is code
at the beginning that turns on address translation so that it appears at
the right place.

In other words, there is nothing for you to change.

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: How Can The Starting Address Of An Image In ELF File BeChanged

[Wolfgang Denk]

In message <OF243EF967.6B4324CF-ON65256E4E.00240CC6@lntinfotech.com> you wrote:
>
> can u guide me 2 some document/link on it or brief it little bit more
> why it is linked to that address ?

Because that was the decision of the designers.

> if it is linked it should be configurable
> bcuz iam using vision ice to download my image.

You get this wrong. The layout of the  Linux  kernel  should  not  be
modified  to  try  adapting  it  to any tools - this will fail sooner
orlater. Instead, get tools that are capable of dealing with the task
you put at them.

VisionIce should be usable to download and start thi  image,  but  it
will  probably  be  of  little use after that. Get yourself a BDI2000
instead ;-)

Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
Inside every old person is a young person wondering what happened.
                              - Terry Pratchett, _Moving Pictures_

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RE: How Can The Starting Address Of An Image In ELF File BeChanged

[VanBaren, Gerald (AGRE)]

The linux kernel runs in VIRTUAL memory space starting at 0xC000_0000.  It needs to be loaded in PHYSICAL space where there is RAM for it to run out of.  When it starts up, it relocates itself to location 0x0000_0000, and then turns on the MMU which it uses to map the physical RAM that it is running out of to virtual memory location 0xC000_0000.

The previous paragraph is extremely simplified.  I strongly suggest you read some kernel and booting HOWTOs and/or buy some books that cover details of the kernel.

One good starting place is Denx' DULG manual
  http://www.denx.de/twiki/bin/view/DULG/Manual
(the title is "Linux for PowerPC Embedded Systems HOWTO", but much/most of it is generic to all the CPUs).

It may be helpful in future questions to identify the CPU (and possibly the board) you are using.

gvb


> -----Original Message-----
> From: owner-linuxppc-embedded@lists.linuxppc.org
> [mailto:owner-linuxppc-embedded@lists.linuxppc.org]On Behalf
> Of Thamarai
> Selvan
> Sent: Friday, March 05, 2004 1:34 AM
> To: Stephen Williams
> Cc: linuxppc-embedded@lists.linuxppc.org
> Subject: Re: How Can The Starting Address Of An Image In ELF File
> BeChanged
>
>
>
> hi
>
> iam still not clear with it
> can u guide me 2 some document/link on it or brief it little bit more
> why it is linked to that address ?
> if it is linked it should be configurable
> bcuz iam using vision ice to download my image.
> Thanks for your immediate reply
>
> with regards
> Thamarai Selvan.G
>
> [ "Stephen Williams" <612dlag102@sneakemail.com> writes: ]
>
> Thamarai Selvan Thamarai.Selvan-at-lntinfotech.com |PPC Linux
> Embedded| wrote:
> >
> > I created the elf file of the kernel using "make vmlinux", when i
> > checked the created system.map i found the the kernel image starting
> > from 0xc0000000. Can any tell where this address is defined or
> > configured? and how can this be changed to 0x0000000 is it possible?
>
> The linux cernel is linked to 0xc0000000, and the entry is really up
> there. In fact, the kernel is loaded starting at 0x0, and
> there is code
> at the beginning that turns on address translation so that it
> appears at
> the right place.
>
> In other words, there is nothing for you to change.
>


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