? 2021-07-09???? 14:49 +0100?Jessica Clarke???

On 9 Jul 2021, at 14:46, Xiang W [off-list ref] wrote:

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? 2021-07-09???? 05:12 +0100?Jessica Clarke???
I tested these patches. Some bugs reported

ld.lld: error: can't create dynamic relocation R_RISCV_32 against
symbol: _fw_start in readonly segment; recompile object files with
-
fPIC or pass '-Wl,-z,notext' to allow text relocations in the
output

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defined in

/home/merle/workspaces/opensbi/build/platform/generic/firmware/fw_d
ynam
ic.elf.ld:9

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referenced by fw_base.S:502

(/home/merle/workspaces/opensbi/firmware/fw_base.S:502)

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/home/merle/workspaces/opensbi/build/platform/generic/firmware/fw_d
ynam
ic.o:(.entry+0x3BC)

This was reported by Bin. Don?t use a Linux triple for something
that?s
neither the Linux kernel nor a Linux userspace executable/library.

Jess

Linux triple?

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Data is stored in the code segment of base.S. Can be fix by:

diff --git a/firmware/fw_base.S b/firmware/fw_base.S
index ee2a51b..f8aea05 100644
--- a/firmware/fw_base.S
+++ b/firmware/fw_base.S

@@ -501,6 +501,7 @@ _skip_trap_exit_rv32_hyp:

?????? /* We don't expect to reach here hence just hang */
?????? j?????? _start_hang

+?????? .data
?????? .align 3
#ifdef FW_PIC
_runtime_offset:

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This patch series is comprised of three parts.

The first patch fixes a warning seen when building with LLVM due
to a
bogus combination of assembly directives.

The second patch adds build system support for using Clang and
LLVM
binutils, provided your Clang is able to locate a libgcc.a in its
search
path.

However, pure LLVM toolchains do not use libgcc, they use
compiler-rt
(libclang_rt.builtins.<arch>.a). We could change the Makefile to
not
hard-code -lgcc and instead use -print-libgcc-file-name, but that
still
requires a bare metal compiler-rt built for the right -march/-
mabi to
be
present, which is often not the case. Moreover, we need very
little
from
libgcc/compiler-rt; RV64 needs nothing, and RV32 only needs 64-
bit
division. Thus, the third patch vendors part of FreeBSD's libquad
and
stops linking against libgcc entirely, allowing OpenSBI to be
built
with
just a cross-compiler. This means that building with any distro-
provided
LLVM just works, as does compiling with the system Clang compiler
and
LLD linker on FreeBSD without any external packages needed
(beyond
GNU
make).

Changes in v3:
? * Fixed the binding warning seen when building with LLVM
? * Provide a default -target when CROSS_COMPILE isn't set so the
??? variable isn't normally required to be set when cross-
compiling
with
??? LLVM (but is still honoured if set).
? * Pass -fuse=bfd when not using LLD to ensure an ld.bfd gets
correctly
??? picked up over a plain ld when ld is LLD. Now we always
explicitly
??? request Clang and GCC use the linker type corresponding to
LD.
This
??? allows BFD to be used on FreeBSD for testing purposes despite
LLD
??? being the system linker.

Changes in v2:
? * Add documentation to README.md
? * Pass -fuse-ld=lld to Clang when using LLD
? * Modify commit message of first commit to explain -N -> -Wl,-N
change
? * Bring back the old ?= uses for the non-CROSS_COMPILE (and,
now,
??? non-LLVM) case; whilst I still think that's how it should be,
it's
??? not required for this patch, just related cleanup I did to
reduce
??? the complexity of adding the LLVM case.

Jessica Clarke (3):
? fw_base: Don't mark fw_platform_init as both global and weak
? Makefile: Support building with Clang and LLVM binutils
? Drop dependency on libgcc by importing part of FreeBSD's
libquad

?Makefile????????????????????????????? |? 65 +++++-
?README.md???????????????????????????? |? 43 +++-
?firmware/fw_base.S??????????????????? |?? 1 -
?lib/utils/libquad/divdi3.c??????????? |? 64 ++++++
?lib/utils/libquad/include/limits.h??? |? 12 ++
?lib/utils/libquad/include/sys/cdefs.h |? 12 ++
?lib/utils/libquad/include/sys/types.h |? 25 +++
?lib/utils/libquad/moddi3.c??????????? |? 66 ++++++
?lib/utils/libquad/objects.mk????????? |? 14 ++
?lib/utils/libquad/qdivrem.c?????????? | 278
++++++++++++++++++++++++++
?lib/utils/libquad/quad.h????????????? | 105 ++++++++++
?lib/utils/libquad/udivdi3.c?????????? |? 52 +++++
?lib/utils/libquad/umoddi3.c?????????? |? 54 +++++
?13 files changed, 782 insertions(+), 9 deletions(-)
?create mode 100644 lib/utils/libquad/divdi3.c
?create mode 100644 lib/utils/libquad/include/limits.h
?create mode 100644 lib/utils/libquad/include/sys/cdefs.h
?create mode 100644 lib/utils/libquad/include/sys/types.h
?create mode 100644 lib/utils/libquad/moddi3.c
?create mode 100644 lib/utils/libquad/objects.mk
?create mode 100644 lib/utils/libquad/qdivrem.c
?create mode 100644 lib/utils/libquad/quad.h
?create mode 100644 lib/utils/libquad/udivdi3.c
?create mode 100644 lib/utils/libquad/umoddi3.c

-- 
2.31.0