U-Boot has up until now built with -fpic for the MIPS architecture,
producing position independent code which uses indirection through a
global offset table, making relocation fairly straightforward as it
simply involves patching up GOT entries.
Using -fpic does however have some downsides. The biggest of these is
that generated code is bloated in various ways. For example, function
calls are indirected through the GOT & the t9 register:
8f998064 lw t9,-32668(gp)
0320f809 jalr t9
Without -fpic the call is simply:
0f803f01 jal be00fc04 <puts>
This is more compact & faster (due to the lack of the load & the
dependency the jump has on its result). It is also easier to read &
debug because the disassembly shows what function is being called,
rather than just an offset from gp which would then have to be looked up
in the ELF to discover the target function.
Another disadvantage of -fpic is that each function begins with a
sequence to calculate the value of the gp register, for example:
3c1c0004 lui gp,0x4
279c3384 addiu gp,gp,13188
0399e021 addu gp,gp,t9
Without using -fpic this sequence no longer appears at the start of each
function, reducing code size considerably.
This patch switches U-Boot from building with -fpic to building with
-fno-pic, in order to gain the benefits described above. The cost of
this is an extra step during the build process to extract relocation
data from the ELF & write it into a new .rel section in a compact
format, plus the added complexity of dealing with multiple types of
relocation rather than the single type that applied to the GOT. The
benefit is smaller, cleaner, more debuggable code. The relocate_code()
function is reimplemented in C to handle the new relocation scheme,
which also makes it easier to read & debug.
Taking maltael_defconfig as an example the size of u-boot.bin built
using the Codescape MIPS 2016.05-06 toolchain (gcc 4.9.2, binutils
2.24.90) shrinks from 254KiB to 224KiB.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: u-boot@lists.denx.de
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Tested-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Provide a default linker script for SPL binaries. Start address
and size of text section and BSS section are configurable. All
sections are arranged in a way that only relevant sections are
kept in the code section for maximum size reduction. All other
sections are kept but moved outside the code section to help
with debugging.
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Acked-by: Marek Vasut <marex@denx.de>
Move setup of -march to arch/mips/Makefile and follow the design on ARM.
Also add a possibility to chose specific CPU tune options.
Signed-off-by: Wills Wang <wills.wang@live.com>
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Prepare sub-folder for device-tree files. Make support for
device-tree on MIPS available in Kbuild/Kconfig.
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
SPL binaries are usually linked to a fixed address in SRAM.
Furthermore SPL binaries do not need to relocate itself. Thus
do not build them as position-independent binaries which helps
to largely reduce the size of SPL binaries.
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Move the option to Kconfig renaming it to CONFIG_HAVE_GENERIC_BOARD.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Alexey Brodkin <abrodkin@synopsys.com>
Commit 79fd7e649e
MIPS: always keep all sections in u-boot ELF binary.
Always keep all sections in u-boot ELF binary. Move all unneeded
sections after _end to avoid allocating space in the final binary.
Also remove .deadcode section which is now obsolete.
removed section .deadcode because the original symptoms were not
visible anymore. Unfortuneatly the binutils bug still exists.
The size of .rel.dyn section is often bigger than needed for all
entries. But objcopy only allocates space as much as required for all
reloc entries. Thus there is a gap between the last entry and
__rel_dyn_end in u-boot.bin. If u-boot is booted from RAM (e.g. in
SPL scenarios) that area could contain garbage data which could lead
to CPU exceptions during relocation.
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Refactor and unify all compiler settings in arch/mips/config.mk.
Also add tune flags for each supported CPU type.
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
This patch allows MIPS boards to make use of generic board, replacing
arch/mips/lib/board.c with common/board_{f,r}.c and struct bd_info with
the asm-generic version.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Always keep all sections in u-boot ELF binary. Move all unneeded
sections after _end to avoid allocating space in the final binary.
Also remove .deadcode section which is now obsolete.
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
The syntax
CROSS_COMIPLE ?= <cross_compiler_prefix>
does not work because config.mk is parsed after
exporting CROSS_COMPILE.
Like Linux Kernel's arch/$(ARCH)/Makefile,
we must write as follows:
ifeq ($(CROSS_COMPILE),)
CROSS_COMPILE := <cross_compiler_prefix>
endif
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Rename OBJCFLAGS to OBJCOPYFLAGS beforehand to use
"cmd_objcopy" in scripts/Makefile.lib in an upcoming commit.
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
The code handles relocation entries with the
following relocation types only:
mips32: R_MIPS_REL32
mips64: R_MIPS_REL+R_MIPS_64
xburst: R_MIPS_REL32
Other relocation entries are skipped without
processing. The code must be extended if other
relocation types must be supported.
Add -pie to LDFLAGS_FINAL to generate the .rel.dyn
fixup table, which will be applied to the relocated
image before transferring control to it.
The CONFIG_NEEDS_MANUAL_RELOC is not needed
after the patch, so remove that as well.
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
All architectures but MIPS are using --gc-sections on final linking.
This patch introduces that feature for MIPS to reduce the memory and
flash footprint.
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Stefan Roese <sr@denx.de>
Cc: Thomas Lange <thomas@corelatus.se>
Cc: Vlad Lungu <vlad.lungu@windriver.com>
Signed-off-by: Shinya Kuribayashi <skuribay@pobox.com>
Rename STANDALONE_LOAD_ADDR into CONFIG_STANDALONE_LOAD_ADDR
and allow that the architecture-specific default value gets
overwritten by defining the value in the board header file.
Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Shinya Kuribayashi <skuribay@ruby.dti.ne.jp>
Cc: Daniel Hellstrom <daniel@gaisler.com>
Cc: Tsi Chung Liew <tsi-chung.liew@freescale.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Also move lib_$ARCH/config.mk to arch/$ARCH/config.mk
This change is intended to clean up the top-level directory structure
and more closely mimic Linux's directory organization.
Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
