On Fri, 16 Oct 2020 16:40:43 -0700
Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote:
> On Fri, Oct 16, 2020 at 4:18 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> > Maybe that helps ? From my builders:
> >
> > # qemu only supports MARCH_Z900. Older kernels select it as default,
> > # but newer kernels may select MARCH_Z196.
> > sed -i -e '/CONFIG_MARCH_Z/d' ${defconfig}
> > sed -i -e '/HAVE_MARCH_Z/d' ${defconfig}
> > echo "CONFIG_MARCH_Z900=y" >> ${defconfig}
> > echo "CONFIG_PCI=y" >> ${defconfig}
>
> $ clang -march=z900 --target=s390x-linux-gnu -c -x c /dev/null -o -
> error: unknown target CPU 'z900'
> note: valid target CPU values are: arch8, z10, arch9, z196, arch10,
> zEC12, arch11, z13, arch12, z14, arch13, z15
>
> Hopefully qemu supports something newer than Z900?
Current QEMU/TCG with the 'qemu' cpu model with give you a
stripped-down z13 that should run fine if you compile to z13. (There's
work ongoing to bump this even to a stripped-down z14, but that needs
some more time.) Anything prior to z13 should be fine as well.
> Or can we change
> arch/s390/Kconfig:255 to use a different arch? Is arch9 == z900???:
My understanding is arch8 == z10 and so on.
>
> 252 config MARCH_Z900
> 253 bool "IBM zSeries model z800 and z900"
> 254 select HAVE_MARCH_Z900_FEATURES
> 255 depends on $(cc-option,-march=z900)
> 256 help
> 257 Select this to enable optimizations for model z800/z900 (2064
> and
> 258 2066 series). This will enable some optimizations that are not
> 259 available on older ESA/390 (31 Bit) only CPUs.
