On 4/22/21 3:22 PM, Stefano Garzarella wrote: > +Cc: io-uring@xxxxxxxxxxxxxxx > +Cc: Pavel Begunkov <asml.silence@xxxxxxxxx> > > Original message: https://www.spinics.net/lists/linux-block/msg67077.html > > On Thu, Apr 22, 2021 at 10:59:42AM +0100, Stefan Hajnoczi wrote: >> On Mon, Apr 19, 2021 at 11:38:07AM -0700, H.J. Lu wrote: >>> On Mon, Apr 19, 2021 at 7:35 AM Stefan Hajnoczi <stefanha@xxxxxxxxxx> wrote: >>> > >>> > On Tue, Apr 13, 2021 at 04:03:19PM +0100, Stefan Hajnoczi wrote: >>> > > The size of C arrays at file scope must be constant. The following >>> > > compiler error occurs with recent upstream glibc (2.33.9000): >>> > > >>> > > CC ucontext-cp >>> > > ucontext-cp.c:31:23: error: variably modified ‘stack_buf’ at file scope >>> > > 31 | unsigned char stack_buf[SIGSTKSZ]; >>> > > | ^~~~~~~~~ >>> > > make[1]: *** [Makefile:26: ucontext-cp] Error 1 >>> > > >>> > > The following glibc commit changed SIGSTKSZ from a constant value to a >>> > > variable: >>> > > >>> > > commit 6c57d320484988e87e446e2e60ce42816bf51d53 >>> > > Author: H.J. Lu <hjl.tools@xxxxxxxxx> >>> > > Date: Mon Feb 1 11:00:38 2021 -0800 >>> > > >>> > > sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305] >>> > > ... >>> > > +# define SIGSTKSZ sysconf (_SC_SIGSTKSZ) >>> > > >>> > > Allocate the stack buffer explicitly to avoid declaring an array at file >>> > > scope. >>> > > >>> > > Cc: H.J. Lu <hjl.tools@xxxxxxxxx> >>> > > Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx> >>> > > --- >>> > > Perhaps the glibc change needs to be revised before releasing glibc 2.34 >>> > > since it might break applications. That's up to the glibc folks. It >>> > > doesn't hurt for liburing to take a safer approach that copes with the >>> > > SIGSTKSZ change in any case. >>> > >>> > glibc folks, please take a look. The commit referenced above broke >>> > compilation of liburing's tests. It's possible that applications will >>> > hit similar issues. Can you check whether the SIGSTKSZ change needs to >>> > be reverted/fixed before releasing glibc 2.34? >>> > >>> >>> It won't be changed for glibc 2.34. >> >> Thanks for the response, H.J. and Paul. >> >> In that case liburing needs this patch. >> > > I think so: > > Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx> Right, and there are already people complaining https://github.com/axboe/liburing/issues/320 -- Pavel Begunkov
