On Sunday 22 November 2015 20:03:26 Russell King - ARM Linux wrote: > On Sun, Nov 22, 2015 at 08:58:08PM +0100, Arnd Bergmann wrote: > > does it work with -mcpu=cortex-a15? I've tried crosstool as versions > > 2.23.52.20130913, 2.24.0.20141017 and 2.25.51.20150518, and they > > all seem to behave as expected, failing with -mcpu=cortex-a9 and > > marvell-pj4 but succeeding with -mcpu=cortex-a15 or marvell-pj4+idiv. > > Appears not: > > root@cubox:~# gcc -O2 -o idiv idiv.c -Wa,-mcpu='cortex-a15+idiv' -marm > /tmp/ccSovg32.s: Assembler messages: > /tmp/ccSovg32.s:32: Error: selected processor does not support ARM mode `udiv ip,r5,r4' > root@cubox:~# gcc -O2 -o idiv idiv.c -Wa,-mcpu='cortex-a15+idiv' -mthumb > /tmp/cchbT3EE.s: Assembler messages: > /tmp/cchbT3EE.s:36: Error: selected processor does not support Thumb mode `udiv r6,r5,r4' > > Same without the +idiv. I've attached files with those instructions, maybe that helps. > > I've also found some /proc/cpuinfo output to cross-reference SoCs > > to their core names. > > > > variant part revision name features > > mmp2: 0 0x581 5 PJ4 idivt > > dove: 0 0x581 5 PJ4 idivt > > Yes, that agrees with my dove. ok. arnd@wuerfel:/tmp$ cat idiv.c unsigned int udiv(unsigned int a, unsigned int b) { return a / b; } int sdiv(int a, int b) { return a / b; } arnd@wuerfel:/tmp$ arm-linux-gnueabihf-gcc -Wall -O2 -mcpu=cortex-a15 idiv.c -c -o idiv-arm.o arnd@wuerfel:/tmp$ objdump -dr idiv-arm.o idiv-arm.o: file format elf32-littlearm Disassembly of section .text: 00000000 <udiv>: 0: fbb0 f0f1 udiv r0, r0, r1 4: 4770 bx lr 6: bf00 nop 00000008 <sdiv>: 8: fb90 f0f1 sdiv r0, r0, r1 c: 4770 bx lr e: bf00 nop arnd@wuerfel:/tmp$ arm-linux-gnueabihf-gcc -Wall -O2 -mcpu=cortex-a15 idiv.c -c -o idiv-thumb.o -mthumb arnd@wuerfel:/tmp$ objdump -dr idiv-thumb.o idiv-thumb.o: file format elf32-littlearm Disassembly of section .text: 00000000 <udiv>: 0: fbb0 f0f1 udiv r0, r0, r1 4: 4770 bx lr 6: bf00 nop 00000008 <sdiv>: 8: fb90 f0f1 sdiv r0, r0, r1 c: 4770 bx lr e: bf00 nop Arnd
Attachment:
idiv-arm.o
Description: application/object
Attachment:
idiv-thumb.o
Description: application/object
unsigned int udiv(unsigned int a, unsigned int b) { return a / b; } int sdiv(int a, int b) { return a / b; }