On 25/07/16 01:30, Nicolas Pitre wrote:
This series provides the necessary changes to allow "flat" executable binaries meant for no-MMU systems to actually run on systems with a MMU. Also thrown in are various cleanups to binfmt_flat.c. This can also be found in the following git repo: git://git.linaro.org/people/nicolas.pitre/linux binfmt_flat_with_mmu
So everyone is in the loop - I have pulled this into my for-linus branch at https://git.kernel.org/cgit/linux/kernel/git/gerg/m68knommu.git/ , excepting patch 15 (ARM specific changes). My continued testing hasn't found any issues on m68k platforms. I can completely boot up with a no-MMU user space and run on an MMU enabled ColdFire platform). I'll like to consider pushing this to Linus nearer the end of the merge window if no-one has any objections. Regards Greg
*Why?* Because developing and testing natively on a large system with lots of RAM makes it so much more convenient to use all the existing profiling tools and debugging facilities that a kernel with lots of RAM can give. And incidentally, those systems with lots of RAM all have a MMU. *Why not use elf_fdpic?* The flat executable format is simple with very small footprint overhead, either in the executables themselves or kernel support. This makes the flat format more suitable than elf_fdpic for very small single user-app embedded systems. And while elf_fdpic binaries can run on MMU systems, flat binaries still couldn't, which just felt wrong. So here it is. The no-MMU support should remain unaffected, confirmed by Greg Ungerer. Tested with MMU on ARM and M68K. Changes since v4: - Isolated architecture specific changes in their own patches for easier review through their own path to mainline. - Added needed m68k register fixup from Greg Ungerer. Changes since v3: - Small cosmetic changes to pr_*(). - Addressed most important checkpatch complaints on the whole source file and patches in this seris. Changes since v2: - Added protection against a corrupted header that could have caused nasty overflows etc. Suggested by Alan Cox. - printk() modernization. Suggested by Greg Ungerer / Geert Uytterhoeven. - Added Greg Ungerer's reviewed-by tag. Changes since v1: - Removed SuperH and Xtensa from the Kconfig rule as they fail to build due to lack of get/put_unaligned_user(). - Clarified some commit logs a bit. diffstat: arch/arm/include/asm/flat.h | 5 +- arch/m68k/include/asm/flat.h | 11 +- arch/m68k/include/asm/processor.h | 2 - fs/Kconfig.binfmt | 3 +- fs/binfmt_elf_fdpic.c | 38 +-- fs/binfmt_flat.c | 525 ++++++++++++++++++-------------- fs/exec.c | 33 ++ include/linux/binfmts.h | 2 + 8 files changed, 345 insertions(+), 274 deletions(-)
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