[U-Boot-Users] [Patch 2/4] U-Boot-V2: ARM: introduce CONFIG_SKIP_RELOCATION

[Sascha Hauer]

On Wed, May 07, 2008 at 09:41:21AM -0500, Menon, Nishanth wrote:
> Sascha,
> > -----Original Message-----
> > From: Sascha Hauer [mailto:s.hauer at pengutronix.de]
> > Sent: Wednesday, May 07, 2008 8:51 AM
> > To: Menon, Nishanth
> > Cc: u-boot-users at lists.sourceforge.net
> > Subject: Re: [Patch 2/4] U-Boot-V2: ARM: introduce CONFIG_SKIP_RELOCATION
> > 
> > On Wed, May 07, 2008 at 06:55:56AM -0500, Menon, Nishanth wrote:
> > > Introduce CONFIG_SKIP_RELOCATION as alternative define. This may be
> > > desired in some conditions where U-Boot is downloaded directly into SRAM
> > > during NAND/Peripheral download mode and is not expected to be
> > > relocated.
> > 
> > If U-Boot is not expected to be relocated, TEXT_BASE should be in SRAM
> > in which case the relocation loop just does nothing. So you end up in
> > saving 12 * 4 bytes of space. Is it really worth to introduce an #ifdef
> > for such a small saving?
> Probably not much of a saving, been looking at the code, and I see
> CONFIG_RELOCATABLE depending on ppc.  It may not be just the savings
> part of 48bytes. There can be additional stuff an SOC might choose to
> do. (ppc start.S also uses the define to save 4 instructions or so).
> Cleaner approach might make sense to remove the CONFIG_RELOCATABLE
> dependency on ppc and make it a global configuration. Allowing any
> platform to choose what ever it wants to do.

CONFIG_RELOCATABLE on powerpc means something different. On arm we start
U-Boot by running it at an address != link address and _copy_ (not
relocate) ourselves to the address we are linked at. On powerpc real
relocation is done if CONFIG_RELOCATABLE is enabled.
Hence the option you wanted to add should better have the name
CONFIG_SKIP_COPY_TO_SDRAM or something like that.

Sascha


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