* Kumar Gala | 2008-10-14 16:23:05 [-0500]: >>Not sure if this is intendent or a gcc bug but with -mno-spe >>the spe opcodes were not used floating point anymore but >>for 64bit save/restore for instance. > >what code is getting generated for you that is causing issue? Without the patch do_syslog() looks like this:
|c0025840 <do_syslog>: |c0025840: 94 21 ff 50 stwu r1,-176(r1) |c0025844: 7c 08 02 a6 mflr r0 |c0025848: 13 21 73 21 evstdd r25,112(r1) |c002584c: 13 41 7b 21 evstdd r26,120(r1) |c0025850: 7c 9a 23 78 mr r26,r4 |c0025854: 13 61 83 21 evstdd r27,128(r1) |c0025858: 7c bb 2b 78 mr r27,r5 |c002585c: 13 e1 a3 21 evstdd r31,160(r1) |c0025860: 7c 7f 1b 78 mr r31,r3 |c0025864: 90 01 00 b4 stw r0,180(r1) |c0025868: 12 21 33 21 evstdd r17,48(r1) |c002586c: 12 41 3b 21 evstdd r18,56(r1) |c0025870: 12 61 43 21 evstdd r19,64(r1) |c0025874: 12 81 4b 21 evstdd r20,72(r1) |c0025878: 12 a1 53 21 evstdd r21,80(r1) |c002587c: 12 c1 5b 21 evstdd r22,88(r1) |c0025880: 12 e1 63 21 evstdd r23,96(r1) |c0025884: 13 01 6b 21 evstdd r24,104(r1) |c0025888: 13 81 8b 21 evstdd r28,136(r1) |c002588c: 13 a1 93 21 evstdd r29,144(r1) |c0025890: 13 c1 9b 21 evstdd r30,152(r1) |c0025894: 48 0f 00 b5 bl c0115948 <cap_syslog> |c0025898: 7c 79 1b 79 mr. r25,r3 |c002589c: 40 82 04 54 bne- c0025cf0 <do_syslog+0x4b0> |c00258a0: 2b 9f 00 0a cmplwi cr7,r31,10 |c00258a4: 41 9d 04 40 bgt- cr7,c0025ce4 <do_syslog+0x4a4> |c00258a8: 3d 20 c0 27 lis r9,-16345 |c00258ac: 57 e0 10 3a rlwinm r0,r31,2,0,29 |c00258b0: 39 29 a6 e4 addi r9,r9,-22812 |c00258b4: 7c 09 00 2e lwzx r0,r9,r0 |c00258b8: 7c 00 4a 14 add r0,r0,r9 |c00258bc: 7c 09 03 a6 mtctr r0 |c00258c0: 4e 80 04 20 bctr |c00258c4: 3b e0 00 00 li r31,0 .... do_syslog() is not the only one. >>1 files changed, 3 insertions(+), 0 deletions(-) >> >>diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile >>index b7d4c4c..3727e4f 100644 >>--- a/arch/powerpc/Makefile >>+++ b/arch/powerpc/Makefile >>@@ -108,7 +108,10 @@ endif >>KBUILD_CFLAGS += $(call cc-option,-mno-altivec) >> >># No SPE instruction when building kernel >>+# (We use all available options to help semi-broken compilers) >>KBUILD_CFLAGS += $(call cc-option,-mno-spe) >>+KBUILD_CFLAGS += $(call cc-option,-mspe=no) > >Why does -mno-spe work? Good question. Without this option and only with -mabi=no-spe the do_syslog() looks like the following: |c0025270 <do_syslog>: |c0025270: 94 21 ff 90 stwu r1,-112(r1) |c0025274: 7c 08 02 a6 mflr r0 |c0025278: be 21 00 34 stmw r17,52(r1) |c002527c: 7c 9a 23 78 mr r26,r4 |c0025280: 90 01 00 74 stw r0,116(r1) |c0025284: 7c bb 2b 78 mr r27,r5 |c0025288: 7c 7f 1b 78 mr r31,r3 |c002528c: 48 0e ce c5 bl c0112150 <cap_syslog> |c0025290: 7c 79 1b 79 mr. r25,r3 |c0025294: 40 82 04 54 bne- c00256e8 <do_syslog+0x478> |c0025298: 2b 9f 00 0a cmplwi cr7,r31,10 |c002529c: 41 9d 04 40 bgt- cr7,c00256dc <do_syslog+0x46c> |c00252a0: 3d 20 c0 26 lis r9,-16346 |c00252a4: 57 e0 10 3a rlwinm r0,r31,2,0,29 |c00252a8: 39 29 36 e4 addi r9,r9,14052 |c00252ac: 7c 09 00 2e lwzx r0,r9,r0 |c00252b0: 7c 00 4a 14 add r0,r0,r9 |c00252b4: 7c 09 03 a6 mtctr r0 |c00252b8: 4e 80 04 20 bctr |c00252bc: 3b e0 00 00 li r31,0 |c00252c0: 48 00 01 c4 b c0025484 <do_syslog+0x214> |c00252c4: 2f 9a 00 00 cmpwi cr7,r26,0 |c00252c8: 41 9e 04 14 beq- cr7,c00256dc <do_syslog+0x46c> |c00252cc: 2f 9b 00 00 cmpwi cr7,r27,0 |c00252d0: 41 9c 04 0c blt- cr7,c00256dc <do_syslog+0x46c> |c00252d4: 41 9e 04 14 beq- cr7,c00256e8 <do_syslog+0x478> |c00252d8: 80 02 03 3c lwz r0,828(r2) |c00252dc: 7f 9a 00 40 cmplw cr7,r26,r0 |c00252e0: 41 9d 04 04 bgt- cr7,c00256e4 <do_syslog+0x474> |c00252e4: 7c 1a 00 50 subf r0,r26,r0 |c00252e8: 39 3b ff ff addi r9,r27,-1 |c00252ec: 7f 89 00 40 cmplw cr7,r9,r0 |c00252f0: 41 9d 03 f4 bgt- cr7,c00256e4 <do_syslog+0x474> |c00252f4: 3d 20 c0 39 lis r9,-16327 |c00252f8: 39 09 8e f8 addi r8,r9,-28936 |c00252fc: 81 29 8e f8 lwz r9,-28936(r9) |c0025300: 80 08 00 04 lwz r0,4(r8) |c0025304: 7f 80 48 00 cmpw cr7,r0,r9 |c0025308: 40 be 00 a4 bne+ cr7,c00253ac <do_syslog+0x13c> |c002530c: 3d 20 c0 04 lis r9,-16380 |c0025310: 39 61 00 14 addi r11,r1,20 |c0025314: 39 29 ae 78 addi r9,r9,-20872 |c0025318: 10 00 02 16 evxor r0,r0,r0 |c002531c: 10 01 0b 21 evstdd r0,8(r1) |c0025320: 7d 1f 43 78 mr r31,r8 boom. > >From my gcc-4.3 info pages: > >`-mspe=YES/NO' > This option has been deprecated. Use `-mspe' and `-mno-spe' > instead. > so it could be gcc bug then and I should open a bugzilla. I didn't know that it is deprecated. >>+KBUILD_CFLAGS += $(call cc-option,-mabi=no-spe) > >is the -mabi=no-spe really needed? It seems to work the other way around (without -mabi=no-spe but with -mabi=no-spe) alteast I did not find anything in do_syslog() or while browsing through the dissasm. I do a boot check tomorrow. > >- k Sebastian _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
