On Wed, 30 Mar 2022 at 11:33, Christophe Leroy <christophe.le...@csgroup.eu> wrote: > > > > Le 30/03/2022 à 13:24, Joel Stanley a écrit : > > Currently the boot wrapper lacks a -mcpu option, so it will be built for > > the toolchain's default cpu. This is a problem if the toolchain defaults > > to a cpu with newer instructions. > > > > We could wire in TARGET_CPU but instead use the oldest supported option > > so the wrapper runs anywhere. > > > > The GCC documentation stays that -mcpu=powerpc64le will give us a > > generic 64 bit powerpc machine: > > > > -mcpu=powerpc, -mcpu=powerpc64, and -mcpu=powerpc64le specify pure > > 32-bit PowerPC (either endian), 64-bit big endian PowerPC and 64-bit > > little endian PowerPC architecture machine types, with an appropriate, > > generic processor model assumed for scheduling purposes. > > > > So do that for each of the three machines. > > > > This bug was found when building the kernel with a toolchain that > > defaulted to powre10, resulting in a pcrel enabled wrapper which fails > > to link: > > > > arch/powerpc/boot/wrapper.a(crt0.o): in function `p_base': > > (.text+0x150): call to `platform_init' lacks nop, can't restore toc; (toc > > save/adjust stub) > > (.text+0x154): call to `start' lacks nop, can't restore toc; (toc > > save/adjust stub) > > powerpc64le-buildroot-linux-gnu-ld: final link failed: bad value > > > > Even with tha bug worked around the resulting kernel would crash on a > > power9 box: > > > > $ qemu-system-ppc64 -nographic -nodefaults -M powernv9 -kernel > > arch/powerpc/boot/zImage.epapr -serial mon:stdio > > [ 7.069331356,5] INIT: Starting kernel at 0x20010020, fdt at > > 0x3068c628 25694 bytes > > [ 7.130374661,3] *********************************************** > > [ 7.131072886,3] Fatal Exception 0xe40 at 00000000200101e4 MSR > > 9000000000000001 > > [ 7.131290613,3] CFAR : 000000002001027c MSR : 9000000000000001 > > [ 7.131433759,3] SRR0 : 0000000020010050 SRR1 : 9000000000000001 > > [ 7.131577775,3] HSRR0: 00000000200101e4 HSRR1: 9000000000000001 > > [ 7.131733687,3] DSISR: 00000000 DAR : 0000000000000000 > > [ 7.131905162,3] LR : 0000000020010280 CTR : 0000000000000000 > > [ 7.132068356,3] CR : 44002004 XER : 00000000 > > > > Link: https://github.com/linuxppc/issues/issues/400 > > Signed-off-by: Joel Stanley <j...@jms.id.au> > > --- > > Tested: > > > > - ppc64le_defconfig > > - pseries and powernv qemu, for power8, power9, power10 cpus > > - buildroot compiler that defaults to -mcpu=power10 (gcc 10.3.0, ld > > 2.36.1) > > - RHEL9 cross compilers (gcc 11.2.1-1, ld 2.35.2-17.el9) > > > > All decompressed and made it into the kernel ok. > > > > ppc64_defconfig did not work, as we've got a regression when the wrapper > > is built for big endian. It hasn't worked for zImage.pseries for a long > > time (at least v4.14), and broke some time between v5.4 and v5.17 for > > zImage.epapr. > > > > arch/powerpc/boot/Makefile | 8 ++++++-- > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile > > index 9993c6256ad2..1f5cc401bfc0 100644 > > --- a/arch/powerpc/boot/Makefile > > +++ b/arch/powerpc/boot/Makefile > > @@ -38,9 +38,13 @@ BOOTCFLAGS := -Wall -Wundef -Wstrict-prototypes > > -Wno-trigraphs \ > > $(LINUXINCLUDE) > > > > ifdef CONFIG_PPC64_BOOT_WRAPPER > > -BOOTCFLAGS += -m64 > > +ifdef CONFIG_CPU_LITTLE_ENDIAN > > +BOOTCFLAGS += -m64 -mcpu=powerpc64le > > else > > -BOOTCFLAGS += -m32 > > +BOOTCFLAGS += -m64 -mcpu=powerpc64 > > +endif > > +else > > +BOOTCFLAGS += -m32 -mcpu=powerpc > > How does that interracts with the following lines ? Isn't it an issue to > have two -mcpu ? > > arch/powerpc/boot/Makefile:$(obj)/4xx.o: BOOTCFLAGS += -mcpu=405 > arch/powerpc/boot/Makefile:$(obj)/ebony.o: BOOTCFLAGS += -mcpu=440 > arch/powerpc/boot/Makefile:$(obj)/cuboot-hotfoot.o: BOOTCFLAGS += -mcpu=405 > arch/powerpc/boot/Makefile:$(obj)/cuboot-taishan.o: BOOTCFLAGS += -mcpu=440 > arch/powerpc/boot/Makefile:$(obj)/cuboot-katmai.o: BOOTCFLAGS += -mcpu=440 > arch/powerpc/boot/Makefile:$(obj)/cuboot-acadia.o: BOOTCFLAGS += -mcpu=405 > arch/powerpc/boot/Makefile:$(obj)/treeboot-iss4xx.o: BOOTCFLAGS += -mcpu=405 > arch/powerpc/boot/Makefile:$(obj)/treeboot-currituck.o: BOOTCFLAGS += > -mcpu=405 > arch/powerpc/boot/Makefile:$(obj)/treeboot-akebono.o: BOOTCFLAGS += > -mcpu=405
Good point, I didn't test the other wrappers. Last one wins as far as -mcpu lines goes, from a quick test. But it might lead to less confusion if I dropped the -mcpu=powerpc change.