On Wed, Aug 28, 2024 at 02:26:08PM +0200, Jason A. Donenfeld wrote: > On Wed, Aug 28, 2024 at 2:24 PM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > > > On Wed, Aug 28, 2024, at 11:18, Jason A. Donenfeld wrote: > > > On Tue, Aug 27, 2024 at 05:53:30PM -0500, Segher Boessenkool wrote: > > >> On Tue, Aug 27, 2024 at 11:08:19AM -0700, Eric Biggers wrote: > > >> > > > >> > Is there a compiler flag that could be used to disable the generation of calls > > >> > to memset? > > >> > > >> -fno-tree-loop-distribute-patterns . But, as always, read up on it, see > > >> what it actually does (and how it avoids your problem, and mostly: learn > > >> what the actual problem *was*!) > > > > > > This might help with various loops, but it doesn't help with the matter > > > that this patch fixes, which is struct initialization. I just tried it > > > with the arm64 patch to no avail. > > > > Maybe -ffreestanding can help here? That should cause the vdso to be built > > with the assumption that there is no libc, so it would neither add nor > > remove standard library calls. Not sure if that causes other problems, > > e.g. if the calling conventions are different. > > >From https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90701: > > | You need -ffreestanding but that is documented to emit memset and > memcpy still. Yeah. '-nostdlib' Do not use the standard system startup files or libraries when linking. This won't help a bit, the compiler will still optimise your initialisation loop to a memset() call, it just won't link to libgcc.a and crt*.o and its ilk (which is not where mem* are implemented in the first place!) Segher
