On 15/07/2019 11:35, Jan Beulich wrote: > With non-empty CONFIG_DOM0_MEM clang5 produces > > dom0_build.c:344:24: error: use of logical '&&' with constant operand > [-Werror,-Wconstant-logical-operand] > if ( !dom0_mem_set && CONFIG_DOM0_MEM[0] ) > ^ ~~~~~~~~~~~~~~~~~~ > dom0_build.c:344:24: note: use '&' for a bitwise operation > if ( !dom0_mem_set && CONFIG_DOM0_MEM[0] ) > ^~ > & > dom0_build.c:344:24: note: remove constant to silence this warning > if ( !dom0_mem_set && CONFIG_DOM0_MEM[0] ) > ~^~~~~~~~~~~~~~~~~~~~~ > 1 error generated. > > Obviously neither of the two suggestions are an option here. Oddly > enough swapping the operands of the && helps, while e.g. casting or > parenthesizing doesn't. Another workable variant looks to be the use of > !! on the constant. > > Signed-off-by: Jan Beulich <jbeul...@suse.com> > --- > I'm open to going the !! or yet some different route. No matter which > one we choose, I'm afraid it is going to remain guesswork what newer > (and future) versions of clang will choke on. > > --- a/xen/arch/x86/dom0_build.c > +++ b/xen/arch/x86/dom0_build.c > @@ -341,7 +341,7 @@ unsigned long __init dom0_compute_nr_pag > unsigned long avail = 0, nr_pages, min_pages, max_pages; > bool need_paging; > > - if ( !dom0_mem_set && CONFIG_DOM0_MEM[0] ) > + if ( CONFIG_DOM0_MEM[0] && !dom0_mem_set ) > parse_dom0_mem(CONFIG_DOM0_MEM);
First and foremost, there is an identical construct on the ARM side, which wants an equivalent adjustment. As to the change, I'm going to suggest what I suggested instead of this the first time around, which is strlen(CONFIG_DOM0_MEM) to make the logic easier to follow. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
