On Fri, Aug 3, 2018 at 8:53 AM, Florian Weimer <fwei...@redhat.com> wrote: > On 08/03/2018 09:11 AM, Andrew Pinski wrote: >> >> Yes fix Links not to use memcpy on the framebuffer. >> It is undefined behavior to use device memory with memcpy. > > > Some (de facto) ABIs require that it is supported, though. For example, the > POWER string functions avoid unaligned loads and stores for this reason > because the platform has the same issue with device memory. And yes, GCC > will expand memcpy on POWER to something that is incompatible with device > memory. 8-(
GCC for AArch64 - use -mstrict-align GCC for AArch32 - use -mno-unaligned-access. If you see unaligned accesses coming out of the compiler for well defined programs then that's a bug. Frequently we see undefined programs that get the compiler to produce traps - atleast one or 2 bugs a year in GCC . > > If we don't want people to use memcpy, we probably need to provide a > credible alternative. I believe a number of packages have rolled their own to take these constraints into account for AArch32, perhaps it needs to be expanded for AArch64 as well. regards Ramana > > Thanks, > Florian
