[U-Boot] [PATCH v2 1/4] mx31pdk: copy SPL directly, not using relocate_code.

Benoît Thébaudeau
2013-05-14T17:10:10Z

Hi Albert,

On Tuesday, May 14, 2013 6:13:55 PM, Albert ARIBAUD wrote:
> Hi Beno?t,
>
> On Tue, 14 May 2013 17:14:12 +0200 (CEST), Beno?t Th?baudeau
> <benoit.thebaudeau@advansee.com> wrote:
>
> > Hi Albert,
> >
> > On Tuesday, May 14, 2013 11:50:27 AM, Albert ARIBAUD wrote:
> > > Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
> > > ---
> > > Changes in v2:
> > > - dropped relocate_code() call from mx31pdk SPL
> > >
> > > board/freescale/mx31pdk/mx31pdk.c | 16 +++++++++++++++-
> > > 1 file changed, 15 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/board/freescale/mx31pdk/mx31pdk.c
> > > b/board/freescale/mx31pdk/mx31pdk.c
> > > index 49158bd..4f6cfee 100644
> > > --- a/board/freescale/mx31pdk/mx31pdk.c
> > > +++ b/board/freescale/mx31pdk/mx31pdk.c
> > > @@ -39,7 +39,21 @@ DECLARE_GLOBAL_DATA_PTR;
> > > #ifdef CONFIG_SPL_BUILD
> > > void board_init_f(ulong bootflag)
> > > {
> > > - relocate_code(CONFIG_SPL_TEXT_BASE);
> > > + /*
> > > + * copy ourselves from where we are running to where we were
> > > + * linked at. Use ulong pointers as all addresses involved
> > > + * are 4-byte-aligned.
> > > + */
> > > + ulong *start_ptr, *end_ptr, *link_ptr, *run_ptr, *dst;
> > > + asm volatile ("ldr %0, =_start" : "=r"(start_ptr));
> > > + asm volatile ("ldr %0, =_end" : "=r"(end_ptr));
> >
> > Why not __image_copy_start/end instead? I know that the result will be the
> > same
> > here, but the naming would be more appropriate. The existing u-boot-spl.lds
> > still gives access to __image_copy_*.
>
> Well, yes, the naming seems appropriate, and I thought and said so
> myself some time ago. But then, I realize that __image_copy_start and
> __image_copy_end are tightly coupled with relocation, and I want to
> avoid creating any additional ties between relocation and SPL just when
> I am severing them. IOW, I want to keep the option of having a reduced
> SPL linker file, distinct from the u-boot one, and where none of
> __image_copy_*, __rel_dyn_* or __dynsym_start exist.

OK, that's fine.

Since _end is linker-generated contrary to the other symbols that you use in
those asm lines, have you checked that no R_ARM_ABS32 relocation data is
generated here? OTOH, -pie is not used with SPL, so there should be no
relocation data at all generated here, and the true final addresses should be in
the binary image.

Best regards,
Beno?t