On 26/02/2019 09.58, Andrew Randrianasulu wrote: > В сообщении от Tuesday 26 February 2019 11:54:12 вы написали: >> On 25/02/2019 18.29, Andrew Randrianasulu wrote: >>> В сообщении от Monday 25 February 2019 19:19:01 Philippe Mathieu-Daudc3a9 >>> >>> написал(а): >>>> Hi Andrew, >>>> >>>> On 2/23/19 1:35 AM, Andrew Randrianasulu wrote: >>>>> Hello! >>>>> >>>>> I just pulled latest git >>>> >>>> [...] >>>> >>>>> and default build with simple ./configure on slackware 14.2 x86-64 box >>>>> failed like this: >>>>> >>>>> root@slax:~/src/qemu# LANG=C make -j 5 >>>>> CHK version_gen.h >>>>> CC qobject/block-qdict.o >>>>> CC util/thread-pool.o >>>>> CC util/main-loop.o >>>>> CC util/qemu-timer.o >>>>> CC util/iohandler.o >>>>> CC util/aio-posix.o >>>>> qobject/block-qdict.c: In function 'qdict_array_split': >>>>> qobject/block-qdict.c:259:9: error: 'subqdict' may be used >>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>> qlist_append_obj(*dst, subqobj ?: QOBJECT(subqdict)); >>>>> ^ >>>> >>>> That's odd, I can not reproduce with a simple ./configure: >>>> >>>> $ cat /etc/slackware-version >>>> Slackware 14.2 >>>> >>>> $ gcc --version >>>> gcc (GCC) 5.5.0 >>> >>> Well, then may be this is false positive, right now another qemu instance >>> is busy inside same chroot, will try patch posted in earlier mail (after >>> removing CFLAG I added for compiling qemu at all after this error). >>> >>> Thanks for trying to reproduce. >> >> Just to be sure: You don't compile with -O3 or -O1 or -O0 in the CFLAGS >> here, do you? > > This time it was -O3, but I got some corruption in ppc64le guest's X, so I > plan > to revert this -O3 back to default ....
Ok, then that's the problem here: GCC often produces some additional "may be unused" warnings with -O3, and we normally only guarantee that QEMU compiles without warnings when using the standard -O2 optimization level. So if you want to compile with -O3, you also have to specify --disable-werror (or add -Wno-error=maybe-unitialized to the CFLAGS). But unless you have really an urgent need for O3, I'd rather recommend to compile with the well-tested O2 optimization level instead. Thomas
