>>> On 24.01.18 at 17:52, <roger....@citrix.com> wrote: > On Wed, Jan 24, 2018 at 09:23:37AM -0700, Jan Beulich wrote: >> >>> On 24.01.18 at 16:48, <roger....@citrix.com> wrote: >> > When indirect_thunk_asm.h is instantiated directly into assembly files >> > CONFIG_INDIRECT_THUNK might not be defined, and thus using .if against >> > it is wrong. >> > >> > Add a check to define CONFIG_INDIRECT_THUNK to 0 if not defined, so >> > that using .if CONFIG_INDIRECT_THUNK is always correct. >> > >> > This suppresses the following clang error: >> > >> > <instantiation>:8:9: error: expected absolute expression >> > .if CONFIG_INDIRECT_THUNK == 1 >> > ^ >> > <instantiation>:1:1: note: while in macro instantiation >> > INDIRECT_BRANCH call %rdx >> > ^ >> > entry.S:589:9: note: while in macro instantiation >> > INDIRECT_CALL %rdx >> > ^ >> >> Why is the same no problem with gas? It wants constant >> expressions with .if too, after all. > > Right, and I cannot figure out why it works when using > -no-integrated-as and not when not using it. The more that I cannot > see CONFIG_INDIRECT_THUNK being unconditionally defined to either 0 or > 1. I guess I'm missing something.
Hmm, it looks to be (half way?) intended behavior for gas to consider "<symbol> == <constant>" always false if <symbol> is undefined (and similarly "<symbol> != <constant>" always true). I'll inquire on the binutils list if this is really meant to remain that way forever, as it's not spelled out that way in the docs. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
