On 2018-04-03 09:18, Alexandre Belloni wrote: > On 02/04/2018 at 22:23:17 +0200, Peter Rosin wrote: >>>> No, but did it again and checked, see transcript below. >>> >>> I don't use devmem2. Is 'readback' information accurate or is it >>> always what's been written? Because when you write 0x33 to 0xFFFFECBC, >>> 0x33 is read back, but just after that, when you read it again it's 0. >> >> Looking at the devmem2 source, it seems very likely that the compiler >> optimizes out the read and thus outputs what has been written. >> > > At least on x86, it is not optimized out.
Looking at the disassembly, they are gone here (not that I'm fluent). I then tried to compile devmem2 with -O0 (instead of -Os) and the read is then fine. So, I guess the devmem2 devs could claim that it's a buildroot issue, but a volatile would certainly have helped... Cheers, Peter
