[Linux-ia64] ia64 compressed makefile target

[Linux-ia64] ia64 compressed makefile target

[Jesse Barnes]

David and Bjorn,

I noticed that the arch/ia64/Makefile 'compressed' target there's a
'--strip-all' arg getting passed to objcopy.  This has the effect of
removing relocation info from the vmlinux binary that we need for
systems w/o memory at the default link address, if I understand
correctly.  Would it be possible to change this option to
'--strip-debug' instead?  I can provide one-line patches for this
against your bitkeeper trees if that's easiest for you...

Thanks,
Jesse

Re: [Linux-ia64] ia64 compressed makefile target

[Andreas Schwab]

Jesse Barnes <jbarnes@sgi.com> writes:

|> David and Bjorn,
|> 
|> I noticed that the arch/ia64/Makefile 'compressed' target there's a
|> '--strip-all' arg getting passed to objcopy.  This has the effect of
|> removing relocation info from the vmlinux binary that we need for
|> systems w/o memory at the default link address, if I understand
|> correctly.  Would it be possible to change this option to
|> '--strip-debug' instead?

How about --strip-unneeded?

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Deutschherrnstr. 15-19, D-90429 Nürnberg
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: [Linux-ia64] ia64 compressed makefile target

[Jesse Barnes]

On Wed, Oct 23, 2002 at 11:26:27AM +0200, Andreas Schwab wrote:
> Jesse Barnes <jbarnes@sgi.com> writes:
> 
> |> David and Bjorn,
> |> 
> |> I noticed that the arch/ia64/Makefile 'compressed' target there's a
> |> '--strip-all' arg getting passed to objcopy.  This has the effect of
> |> removing relocation info from the vmlinux binary that we need for
> |> systems w/o memory at the default link address, if I understand
> |> correctly.  Would it be possible to change this option to
> |> '--strip-debug' instead?
> 
> How about --strip-unneeded?
> 
> Andreas.

Even better.

Thanks,
Jesse

RE: [Linux-ia64] ia64 compressed makefile target

[Luck, Tony]

Or perhaps David will take the CONFIG_IA64_VMAP_KERNEL
patch that I posted a week ago which also allows the
kernel to run on systems without memory at the default
link address.  Admittedly it's more than one line, but
it contains much of the same infrastructure that is
needed to support kernel text replication.

-Tony

-----Original Message-----
From: Jesse Barnes [mailto:jbarnes@sgi.com]
Sent: Tuesday, October 22, 2002 8:21 PM
To: linux-ia64@linuxia64.org; davidm@hpl.hp.com; bjorn_helgaas@hp.com
Subject: [Linux-ia64] ia64 compressed makefile target


David and Bjorn,

I noticed that the arch/ia64/Makefile 'compressed' target there's a
'--strip-all' arg getting passed to objcopy.  This has the effect of
removing relocation info from the vmlinux binary that we need for
systems w/o memory at the default link address, if I understand
correctly.  Would it be possible to change this option to
'--strip-debug' instead?  I can provide one-line patches for this
against your bitkeeper trees if that's easiest for you...

Thanks,
Jesse

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RE: [Linux-ia64] ia64 compressed makefile target

[David Mosberger]

>>>>> On Wed, 23 Oct 2002 10:46:32 -0700, "Luck, Tony" <tony.luck@intel.com> said:

  Tony> Or perhaps David will take the CONFIG_IA64_VMAP_KERNEL patch
  Tony> that I posted a week ago which also allows the kernel to run
  Tony> on systems without memory at the default link address.
  Tony> Admittedly it's more than one line, but it contains much of
  Tony> the same infrastructure that is needed to support kernel text
  Tony> replication.

I don't have a strong preference either way, but I do have some
concerns about the VMAP_KERNEL.  I really dislike the fact that it
requires different versions of virtual-to-physical translations for
kernel addresses.  No other platform does that, so it will be a source
of continual worry.  Jesse, could you describe your approach a little
more?  I assume you link the kernel with "ld -r" and have an elilo
that applies the relocations?

	--david

RE: [Linux-ia64] ia64 compressed makefile target

[Luck, Tony]

>>>>> On Wed, 23 Oct 2002 10:46:32 -0700, "Luck, Tony" <tony.luck@intel.com>
said:

  Tony> Or perhaps David will take the CONFIG_IA64_VMAP_KERNEL patch
  Tony> that I posted a week ago which also allows the kernel to run
  Tony> on systems without memory at the default link address.
  Tony> Admittedly it's more than one line, but it contains much of
  Tony> the same infrastructure that is needed to support kernel text
  Tony> replication.

> I don't have a strong preference either way, but I do have some
> concerns about the VMAP_KERNEL.  I really dislike the fact that it
> requires different versions of virtual-to-physical translations for
> kernel addresses.  No other platform does that, so it will be a source
> of continual worry.  Jesse, could you describe your approach a little
> more?  I assume you link the kernel with "ld -r" and have an elilo
> that applies the relocations?

I'm not sure that the mapping the kernel is quite as scary as it
appears to be:
1) All of the places where we need to take special care are in
   initialization code.
2) Code that can be loaded as a module (which is a whole lot of
   code) cannot make any assumptions about __pa() working on
   addresses in .text/.data/.bss

A relocating elilo sounds interesting too (it passes the "don't
do things in the kernel unless you really have to" test).

-Tony

Re: [Linux-ia64] ia64 compressed makefile target

[Jesse Barnes]

On Wed, Oct 23, 2002 at 12:01:29PM -0700, David Mosberger wrote:
> I don't have a strong preference either way, but I do have some
> concerns about the VMAP_KERNEL.  I really dislike the fact that it
> requires different versions of virtual-to-physical translations for
> kernel addresses.  No other platform does that, so it will be a source
> of continual worry.  Jesse, could you describe your approach a little
> more?  I assume you link the kernel with "ld -r" and have an elilo
> that applies the relocations?

Elilo 3.1 supports relocation, but now that I look, we're not passing -r
to ld when the kernel is linked, which makes me wonder why it works at
all.  But I've confirmed that a kernel stripped with --strip-all doesn't
boot, while the same binary stripped with --strip-debug does (haven't
tried --strip-unneeded, but that should work too).  I can look into it
more if you're not comfortable with the change, and maybe Tony has
something to add?

Thanks,
Jesse

Re: [Linux-ia64] ia64 compressed makefile target

[Jack Steiner]

> 
> On Wed, Oct 23, 2002 at 12:01:29PM -0700, David Mosberger wrote:
> > I don't have a strong preference either way, but I do have some
> > concerns about the VMAP_KERNEL.  I really dislike the fact that it
> > requires different versions of virtual-to-physical translations for
> > kernel addresses.  No other platform does that, so it will be a source
> > of continual worry.  Jesse, could you describe your approach a little
> > more?  I assume you link the kernel with "ld -r" and have an elilo
> > that applies the relocations?
> 
> Elilo 3.1 supports relocation, but now that I look, we're not passing -r
> to ld when the kernel is linked, which makes me wonder why it works at
> all.  But I've confirmed that a kernel stripped with --strip-all doesn't
> boot, while the same binary stripped with --strip-debug does (haven't
> tried --strip-unneeded, but that should work too).  I can look into it
> more if you're not comfortable with the change, and maybe Tony has
> something to add?
> 
> Thanks,
> Jesse
> 

There is a second way to specify that the kernel is relocatable.

We put a 
	relocatable

directive in the elilo.conf file.

I think either way works.



-- 
Thanks

Jack Steiner    (651-683-5302)   (vnet 233-5302)      steiner@sgi.com

Re: [Linux-ia64] ia64 compressed makefile target

[David Mosberger]

>>>>> On Wed, 23 Oct 2002 13:49:35 -0700, Jesse Barnes <jbarnes@sgi.com> said:

  Jesse> Elilo 3.1 supports relocation, but now that I look, we're not
  Jesse> passing -r to ld when the kernel is linked, which makes me
  Jesse> wonder why it works at all.

Hmmh, I may be dense here, but I don't see any code that applies
relocations.  I do see code in Elilo that allows loading the kernel at
a non-default address, but not much more than that.  Can you clarify?

	--david

Re: [Linux-ia64] ia64 compressed makefile target

[Jesse Barnes]

On Wed, Oct 23, 2002 at 02:08:14PM -0700, David Mosberger wrote:
> >>>>> On Wed, 23 Oct 2002 13:49:35 -0700, Jesse Barnes <jbarnes@sgi.com> said:
> 
>   Jesse> Elilo 3.1 supports relocation, but now that I look, we're not
>   Jesse> passing -r to ld when the kernel is linked, which makes me
>   Jesse> wonder why it works at all.
> 
> Hmmh, I may be dense here, but I don't see any code that applies
> relocations.  I do see code in Elilo that allows loading the kernel at
> a non-default address, but not much more than that.  Can you clarify?

Yeah, I think I'm missing something too.  I'll poke around some more.

Jesse