Re: [PATCH v2] dl: Use "adr" assembler command to get proper load address on ARM

[Szabolcs Nagy <Szabolcs.Nagy@arm.com>]

The 10/15/2021 16:53, Fāng-ruì Sòng wrote:
> On Fri, Oct 15, 2021 at 6:00 AM Lukasz Majewski <lukma@denx.de> wrote:
> > On Fri, 15 Oct 2021 05:21:23 -0700
> > "H.J. Lu" <hjl.tools@gmail.com> wrote:
> > > I think either prelink should be fixed not to prelink ld.so or Yocto
> > > should be fixed not to prelink ld.so.
> >
> > Could you explain why?
> >
> > Was the relocation of ld.so (I guess that ld.so = ld-linux-arm.so) a
> > bug from the very beginning and it was apparent just now?
> 
> Prelinking improves application relocation performance but prelinking
> ld.so itself doesn't provide any saving.
> It is very likely that the prelink program doesn't intend to prelink
> ld.so. It just doesn't provide a diagnostic.
> If we look at the problem from this angle, prelinking ld.so is a pilot
> error: OE/Yocto used an unsupported thing which happened to work in
> the past.
> Now, the unsupported (well, it can be supported if prelink correctly
> prelinks ld.so) thing fails.
> I sent the original commit trying to untangle the messy arm code.
> Although Szabolcs's version is still short, I'd prefer we don't work
> around glibc for error/prelink errors.

i don't know much about pelinking, but i'd expect that ld.so
has to be prelinked for it to work:

if the kernel can load ld.so anywhere it will conflict with
other libraries that prelinking allocated to a fixed location.

instead ld.so has to be prelinked to an offset that comes after
all other prelinked libraries in the system, then the kernel
will place it after all other libraries at runtime.

i don't have a prelinked system to check if this is the case.