On Thu 09 Apr 01:22 PDT 2020, Peng Fan wrote: > To arm64, "dc zva, dst" is used in memset. > Per ARM DDI 0487A.j, chapter C5.3.8 DC ZVA, Data Cache Zero by VA, > > "If the memory region being zeroed is any type of Device memory, > this instruction can give an alignment fault which is prioritized > in the same way as other alignment faults that are determined > by the memory type." > > On i.MX platforms, when elf is loaded to onchip TCM area, the region > is ioremapped, so "dc zva, dst" will trigger abort. > > Since memset is not strictly required, let's drop it. > This would imply that we trust that the firmware doesn't expect remoteproc to zero out the memory, which we've always done. So I don't think we can say that it's not required. > Signed-off-by: Peng Fan <peng.fan@xxxxxxx> > --- > drivers/remoteproc/remoteproc_elf_loader.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/drivers/remoteproc/remoteproc_elf_loader.c b/drivers/remoteproc/remoteproc_elf_loader.c > index 16e2c496fd45..cc50fe70d50c 100644 > --- a/drivers/remoteproc/remoteproc_elf_loader.c > +++ b/drivers/remoteproc/remoteproc_elf_loader.c > @@ -238,14 +238,11 @@ int rproc_elf_load_segments(struct rproc *rproc, const struct firmware *fw) > memcpy(ptr, elf_data + offset, filesz); > > /* > - * Zero out remaining memory for this segment. > + * No need zero out remaining memory for this segment. > * > * This isn't strictly required since dma_alloc_coherent already > - * did this for us. albeit harmless, we may consider removing > - * this. > + * did this for us. In the case of recovery this comment is wrong, we do not dma_alloc_coherent() the carveout during a recovery. And in your case you ioremapped existing TCM, so it's never true. > */ > - if (memsz > filesz) > - memset(ptr + filesz, 0, memsz - filesz); So I think you do want to zero out this region. Question is how we do it... Regards, Bjorn > } > > if (ret == 0) > -- > 2.16.4 >
