On 4/21/22 05:23, Rich Felker wrote: > On Wed, Apr 20, 2022 at 10:04:32PM +0200, Arnd Bergmann wrote: >> On Wed, Apr 20, 2022 at 7:47 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: >>> >>> Yeah, I was trying to understand why systems were using binfmt_flat and >>> not binfmt_elf, given the mention of elf2flat -- is there really such a >>> large kernel memory footprint savings to be had from removing >>> binfmt_elf? >> >> I think the main reason for using flat binaries is nommu support on >> m68k, xtensa and risc-v. The regular binfmt_elf support requires >> an MMU, and the elf-fdpic variant is only available for arm and sh >> at this point (the other nommu architectures got removed over time). > > I believe I made the elf-fdpic loader so that it's capable of loading > normal non-fdpic elf files on nommu (1bde925d23), unless somebody > broke that. I also seem to recall that capability being added to the > main elf loader later. Last time I checked, building shared libraries usable with nommu riscv required gcc/ld options that were not supported for riscv (PIE related stuff). So removing the kernel support for shared flat libs is fine with me. -- Damien Le Moal Western Digital Research
