On Mon, 19 Sep 2011, Rob Clark wrote: > On Mon, Sep 19, 2011 at 10:39 AM, Will Deacon <will.dea...@arm.com> wrote: > > Arnd, > > > > On Mon, Sep 19, 2011 at 08:15:45AM +0100, Arnd Bergmann wrote: > >> Assuming that we can prevent any funny stuff from going into such an ABI, > >> we only need to worry about the warts of the current ABI for ARM specific > >> considerations. The one thing that I've noticed before is that structs > >> on ARM (at least on one of the ABIs, forgot which) are padded to 32 bits, > >> even if all members inside are smaller. > > > > This is only the case for the old ABI. EABI lays out structures so that they > > are aligned to their most aligned member and padded to be the smallest > > possible multiple of that alignment which can contain all of their aligned > > members. > > Hmm, so then since you can build the kernel w/ OABI compatibility, it > seems like structs should always have padding fields to force them to > be a multiple of 32bits...
Depends what you want to achieve. The OABI compat is there only to allow _most_ old binaries to execute on a modern system. When I wrote that code, I left out ioctl ABI compatibility issues because there are simply too many of them, and in practice the most often used ones just work already. A notable exception is ALSA. So at this point I think there is no point caring too much about the OABI. Nicolas _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
