On Tue, Jul 9, 2019 at 5:26 AM Russell King - ARM Linux admin <[email protected]> wrote: > > On Tue, Jul 09, 2019 at 02:17:58PM +0200, Linus Walleij wrote: > > On Mon, Jul 8, 2019 at 10:31 PM Arnd Bergmann <[email protected]> wrote: > > > > > -#define xip_iprefetch() do { asm volatile (".rep 8; nop; .endr"); > > > } while (0) > > > +#define xip_iprefetch() do { > > > \ > > > + asm volatile ("nop; nop; nop; nop; nop; nop; nop; nop;"); \ > > > +} while (0) \ > > > > This is certainly an OK fix since we use a row of inline nop at > > other places. > > > > However after Russell explained the other nops I didn't understand I located > > these in boot/compressed/head.S as this in __start: > > > > .rept 7 > > __nop > > .endr > > #ifndef CONFIG_THUMB2_KERNEL > > mov r0, r0 > > #else > > > > And certainly this gets compiled, right? > > > > So does .rept/.endr work better than .rep/.endr, is it simply mis-spelled? > > > > I.e. s/.rep/.rept/g > > ? > > > > In that case we should explain in the commit that .rep doesn't work > > but .rept does. > > According to the info pages for gas: > > 7.96 `.rept COUNT' > ================== > > Repeat the sequence of lines between the `.rept' directive and the next > `.endr' directive COUNT times. > > So yes, ".rep" is mis-spelled, and it brings up the obvious question: > why isn't gas issuing an error for ".rep"? There is no mention of > ".rep" in the manual.
I swear I had looked this up somewhere and found that GNU as and clang's integrated assembler supported alternative spellings for assembly directives. Just checked the manual https://ftp.gnu.org/old-gnu/Manuals/gas-2.9.1/html_chapter/as_7.html#SEC116 and indeed no mention of the alternatives...must have been looking at the source... -- Thanks, ~Nick Desaulniers
