[PATCH v4 3/5] firmware: Explicitly pass -pie to the linker, not just the driver

[Bin Meng]

On Sat, Jul 10, 2021 at 10:56 AM Bin Meng <bmeng.cn at gmail.com> wrote:
>
> On Sat, Jul 10, 2021 at 3:35 AM Jessica Clarke <jrtc27 at jrtc27.com> wrote:
> >
> > When using Clang with a bare-metal triple, -pie does not get passed to
> > the linker as it's not normally a thing that makes sense. However, in
> > our case it is, and manually forwarding it on works as desired, so do so
> > to fully support FW_PIC with Clang, including when linking with LLD.
> > ---
> >  firmware/objects.mk | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/firmware/objects.mk b/firmware/objects.mk
> > index ce91c2f..3bc83cd 100644
> > --- a/firmware/objects.mk
> > +++ b/firmware/objects.mk
> > @@ -21,7 +21,7 @@ ifeq ($(FW_PIC),y)
> >  firmware-genflags-y += -DFW_PIC
> >  firmware-asflags-y  += -fpic
> >  firmware-cflags-y   += -fPIE -pie
> > -firmware-ldflags-y  +=  -Wl,--no-dynamic-linker
> > +firmware-ldflags-y  +=  -Wl,--no-dynamic-linker -Wl,-pie
> >  endif
>
> Does this manual forwarding also work for GNU ld? If so, I think we
> don't need to detect bare-metal triple and turn off FW_PIC in
> Makefile?

I just built a riscv64-unknown-elf-gcc toolchain and used it to build
the current HEAD of opensbi/master. Indeed it's broken that pie is not
supported with the bare-metal triple.

The GNU ld simply complains:

 ELF       platform/generic/firmware/payloads/test.elf
/opt/riscv-unknown-elf/lib/gcc/riscv64-unknown-elf/10.1.0/../../../../riscv64-unknown-elf/bin/ld.bfd:
-pie not supported

Regards,
Bin