On Fri, Feb 12, 2021 at 09:40:59AM -0500, Steven Rostedt wrote: > On Thu, 11 Feb 2021 13:48:48 -0800 > Jason Gerecke <[email protected]> wrote: > > > When compiling an external kernel module with `-O0` or `-O1`, the following > > compile error may be reported: > > > > ./arch/x86/include/asm/jump_label.h:25:2: error: impossible constraint > > in ‘asm’ > > 25 | asm_volatile_goto("1:" > > | ^~~~~~~~~~~~~~~~~ > > > > It appears that these lower optimization levels prevent GCC from detecting > > that the key/branch arguments can be treated as constants and used as > > immediate operands. To work around this, explicitly add the `const` label. > > Yes this makes sense. The "i" constraint needs to be a constant.
Right, using -O[01] seems a little daft though. But yeah, that patch is correct and won't cause harm. I've queued it for after the next merge window.
