On Wed, Sep 20, 2023 at 05:22:33PM +1000, Greg Ungerer wrote: > On 20/9/23 01:14, Matthew Wilcox wrote: > > I have a 68020 book; what I don't have is a Coldfire manual. > > You can find it here: https://www.nxp.com/docs/en/reference-manual/CFPRM.pdf Thanks, Greg. This is almost good: static inline bool xor_unlock_is_negative_byte(unsigned long mask, volatile unsigned long *p) { #ifdef CONFIG_COLDFIRE __asm__ __volatile__ ("eorl %1, %0" : "+m" (*p) : "d" (mask) : "memory"); return *p & (1 << 7); #else char result; char *cp = (char *)p + 3; /* m68k is big-endian */ __asm__ __volatile__ ("eor.b %1, %2; smi %0" : "=d" (result) : "di" (mask), "o" (*cp) : "memory"); return result; #endif } folio_end_read() does about as well as can be expected: 00000708 <folio_end_read>: 708: 206f 0004 moveal %sp@(4),%a0 70c: 7009 moveq #9,%d0 70e: 4a2f 000b tstb %sp@(11) 712: 6602 bnes 716 <folio_end_read+0xe> 714: 7001 moveq #1,%d0 716: b190 eorl %d0,%a0@ 718: 2010 movel %a0@,%d0 71a: 4a00 tstb %d0 71c: 6a0c bpls 72a <folio_end_read+0x22> 71e: 42af 0008 clrl %sp@(8) 722: 2f48 0004 movel %a0,%sp@(4) 726: 6000 fcfe braw 426 <folio_wake_bit> 72a: 4e75 rts However, it seems that folio_unlock() could shave off an instruction: 00000918 <folio_unlock>: 918: 206f 0004 moveal %sp@(4),%a0 91c: 7001 moveq #1,%d0 91e: b190 eorl %d0,%a0@ 920: 2010 movel %a0@,%d0 922: 4a00 tstb %d0 924: 6a0a bpls 930 <folio_unlock+0x18> 926: 42a7 clrl %sp@- 928: 2f08 movel %a0,%sp@- 92a: 4eba fafa jsr %pc@(426 <folio_wake_bit>) 92e: 508f addql #8,%sp 930: 4e75 rts We could use eori instead of eorl, at least according to table 3-9 on page 3-8: EOR Dy,<ea>x L Source ^ Destination → Destination ISA_A EORI #<data>,Dx L Immediate Data ^ Destination → Destination ISA_A but gas is unhappy with everything I've tried to use eori. I'm building with stmark2_defconfig, which I assume should work.
