On March 4, 2017 4:33:49 PM PST, Borislav Petkov <b...@suse.de> wrote: >On Sat, Mar 04, 2017 at 04:23:17PM -0800, h...@zytor.com wrote: >> What are the compilation flags? It may be that gcc still does TRT >> depending on this call site. I'd check what gcc6 or 7 generates, >> though. > >Well, I don't think that matters: if you're building a kernel on one >machine to boot on another machine, the compiler can't know at build >time what the best MOVS* variant would be for the target machine. >That's >why we're doing the alternatives patching at *boot* time. > >However, if the size is small enough, the CALL/patch overhead would be >definitely too much. > >Hmm, I wish we were able to say, "let gcc decide for small sizes and >let >us do the patching for larger ones."
That's what the -march= and -mtune= option do! -- Sent from my Android device with K-9 Mail. Please excuse my brevity.