[U-Boot] [PATCH v3 0/6] Introduce generic relocation feature
Albert ARIBAUD
albert.u.boot at aribaud.net
Wed Jan 18 08:28:47 CET 2012
Hi Simon,
Le 26/12/2011 19:24, Simon Glass a écrit :
> (I am resending this rebased so I can continue with this board-unification
> work and allow people to review patches. There were some comments on the
> v2 series but my questions have been sitting on the list for 2 weeks so it
> is probably time for a new series.)
>
> This is the second patch series aiming to unify the various board.c files
> in each architecture into a single one. This series implements a generic
> relocation feature, which is the bridge between board_init_f() and
> board_init_r(). It then moves ARM over to use this framework, as an
> example.
>
> On ARM the relocation code is duplicated for each CPU yet it
> is the same. We can bring this up to the arch level. But since (I believe)
> Elf relocation is basically the same process for all archs, there is no
> reason not to bring it up to the generic level.
>
> Each architecture which uses this framework needs to provide a function
> called arch_elf_relocate_entry() which processes a single relocation
> entry. This is a static inline function to reduce code size overhead.
Agreed.
> For ARM, a new arch/arm/lib/proc.S file is created, which holds generic
> ARM assembler code (things that cannot be written in C and are common
> functions used by all ARM CPUs). This helps reduce duplication. Interrupt
> handling code and perhaps even some startup code can move there later.
>
> It may be useful for other architectures with a lot of different CPUs
> to have a similar file.
NAK for several reasons:
1. The code that goes on proc.S is already in start.S, which already
contains "things which cannot be written in C and are common functions
used by all ARM CPUs". Granted, right now start.S is duplicated in
multiple CPU directories; so the thing to do is to merge all ARM start.S
files into a single one, rather than merging only one of its parts.
2. There is no interest in moving this segment of code from all start.S
files into a new proc.S file: there is no gain is code size obviously,
and there is an increase in source file count.
3. I consider that files should contain 'things' based on their common
/functionality/, not on their similar /nature/, and "going about
starting up U-Boot" is a functionality.
Note that eventually, having a single start.S will achieve the same
effect as this 'proc.S' patch.
Note also that this start.S commonalization should be a completely
different patch set.
> Code size on my ARMv7 system increases by 54 bytes with generic
> relocation. This overhead is mostly just literal pool access and setting
> up to call the relocated U-Boot at the end.
>
> On my system, execution time increases from 10.8ms to 15.6ms due to the
> less efficient C implementations of the copy and zero loops. If execution
> time is of concern, you can define CONFIG_USE_ARCH_MEMSET and
> CONFIG_USE_ARCH_MEMCPY to reduce it. For met this reduces relocation time
> to 5.4ms, i.e. twice as fast as the old system.
Side question: is there any reason not to define these CONFIG options
systematically?
> One problem remains which causes mx31pdk to fail to build. It doesn't
> have string.c in its SPL code and the architecture-specific versions of
> memset()/memcpy() are too large. I propose to add a local change to
> reloc.c that uses inline code for boards that use the old legacy SPL
> framework. We can remove it later. This is not included in v2 but I am
> interested in comments on this approach. An alternative would be just
> to add simple memset()/memcpy() functions just for this board (and one
> other affected MX31 board).
I am not too fond of the "later removal" approach. In my experience,
this invariably tends to the "old bloat in the code no one knows the
reason of" situations.
> Changes in v2:
> - Use CONFIG_SYS_SKIP_RELOC instead of CONFIG_SYS_LEGACY_BOARD
> - Import asm-generic/sections.h from Linux and add U-Boot extras
> - Squash generic link symbols patch into generic relocation patch
> - Move reloc.c into common/
> - Add function comments
> - Use memset, memcpy instead of inline code
> - Add README file for relocation
> - Invalidate I-cache when we jump to relocated code
> - Use an inline relocation function to reduce code size
> - Make relocation symbols global so we can use them outside start.S
>
> Changes in v3:
> - Remove the 'reloc' tag from each commit
> - Rebase to master
>
> Simon Glass (6):
> Create reloc.h and include it where needed
> define CONFIG_SYS_SKIP_RELOC for all archs
> Add generic relocation feature
> arm: Add processor function library
> arm: Move over to generic relocation
> arm: Remove unused code in start.S
>
> README | 4 +
> arch/arm/cpu/arm1136/start.S | 133 ++------------
> arch/arm/cpu/arm1176/start.S | 214 ++-------------------
> arch/arm/cpu/arm720t/start.S | 127 ++-----------
> arch/arm/cpu/arm920t/start.S | 135 ++------------
> arch/arm/cpu/arm925t/start.S | 135 ++------------
> arch/arm/cpu/arm926ejs/davinci/spl.c | 1 +
> arch/arm/cpu/arm926ejs/start.S | 144 ++-------------
> arch/arm/cpu/arm946es/start.S | 130 ++-----------
> arch/arm/cpu/arm_intcm/start.S | 135 ++------------
> arch/arm/cpu/armv7/omap-common/spl.c | 1 +
> arch/arm/cpu/armv7/start.S | 140 ++------------
> arch/arm/cpu/ixp/start.S | 127 ++-----------
> arch/arm/cpu/lh7a40x/start.S | 124 ++-----------
> arch/arm/cpu/pxa/start.S | 138 ++------------
> arch/arm/cpu/s3c44b0/start.S | 127 ++-----------
> arch/arm/cpu/sa1100/start.S | 124 ++-----------
> arch/arm/include/asm/reloc.h | 56 ++++++
> arch/arm/lib/Makefile | 2 +
> arch/arm/lib/board.c | 1 +
> arch/arm/lib/proc.S | 40 ++++
> arch/avr32/config.mk | 3 +
> arch/avr32/lib/board.c | 1 +
> arch/blackfin/config.mk | 3 +
> arch/m68k/config.mk | 3 +
> arch/m68k/lib/board.c | 1 +
> arch/microblaze/config.mk | 3 +
> arch/mips/config.mk | 3 +
> arch/mips/lib/board.c | 1 +
> arch/nds32/config.mk | 3 +
> arch/nds32/lib/board.c | 1 +
> arch/nios2/config.mk | 3 +
> arch/powerpc/config.mk | 3 +
> arch/powerpc/lib/board.c | 1 +
> arch/sandbox/config.mk | 3 +
> arch/sh/config.mk | 3 +
> arch/sparc/config.mk | 3 +
> arch/x86/config.mk | 3 +
> arch/x86/lib/board.c | 1 +
> board/freescale/mpc8313erdb/mpc8313erdb.c | 1 +
> board/freescale/mpc8315erdb/mpc8315erdb.c | 1 +
> board/samsung/smdk6400/smdk6400_nand_spl.c | 1 +
> board/sheldon/simpc8313/simpc8313.c | 1 +
> common/Makefile | 4 +
> common/reloc.c | 121 ++++++++++++
> doc/README.relocation | 87 +++++++++
> include/asm-generic/sections.h | 92 +++++++++
> include/common.h | 2 +-
> include/reloc.h | 54 +++++
> nand_spl/board/freescale/mpc8536ds/nand_boot.c | 1 +
> nand_spl/board/freescale/mpc8569mds/nand_boot.c | 1 +
> nand_spl/board/freescale/mpc8572ds/nand_boot.c | 1 +
> nand_spl/board/freescale/mx31pdk/Makefile | 8 +-
> nand_spl/board/freescale/mx31pdk/u-boot.lds | 1 +
> nand_spl/board/freescale/p1010rdb/nand_boot.c | 1 +
> nand_spl/board/freescale/p1023rds/nand_boot.c | 1 +
> nand_spl/board/freescale/p1_p2_rdb/nand_boot.c | 1 +
> nand_spl/board/freescale/p1_p2_rdb_pc/nand_boot.c | 1 +
> nand_spl/board/karo/tx25/Makefile | 8 +-
> nand_spl/board/karo/tx25/u-boot.lds | 1 +
> nand_spl/nand_boot_fsl_nfc.c | 1 +
> 61 files changed, 705 insertions(+), 1765 deletions(-)
> create mode 100644 arch/arm/include/asm/reloc.h
> create mode 100644 arch/arm/lib/proc.S
> create mode 100644 common/reloc.c
> create mode 100644 doc/README.relocation
> create mode 100644 include/asm-generic/sections.h
> create mode 100644 include/reloc.h
Amicalement,
--
Albert.
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