On Thu, May 21, 2020 at 04:38:47PM +0200, Paolo Bonzini wrote: > On 30/04/20 11:40, Peter Maydell wrote: > >> This does not "drop" a write to a r/o region -- it causes it to generate > >> whatever the guest architecture's equivalent of a bus error is (eg data > >> abort on Arm). > > > > More generally, this change seems a bit odd: currently we do not > > check the mr->readonly flag here, but in general guests don't get > > to write to ROM areas. Where is that check currently done > > Writes to ROM are directed to mr->ops unassigned_mem_ops. Because _all_ > ram-device reads and writes go through the ops, for ram-device we have > to stick the check for mr->readonly in the ops. > > On one hand, I was quite surprised to see that unassigned_mem_write does > not return MEMTX_ERROR now that I looked at it. > > On the other hand, we should use MEMTX_ERROR in patch 2 as well, if we > decide it's the way to go. > > (Sorry Yan for the late response). > hi Paolo, thanks for your reply and never mind :)
But there's one thing I just can't figure out the reason and eagerly need your guide. why do we have to convert all .write operations to .write_with_attrs and return MEMTX_ERROR? because of the handling of writes to read-only region? however, it seems that all regions have to handle this case, so ultimately we have to convert all .write to .write_with_attrs and there would be no .write operations any more? Thanks Yan
