On 25 November 2016 at 01:29, Christian Lamparter <chunk...@googlemail.com> wrote: > Hello, > > On Friday, November 25, 2016 12:03:54 AM CET Yousong Zhou wrote: >> An ARM Cortex-A machine provided by QEMU. >> >> Kernel drivers enabled: >> >> - pl011, uart >> - pl031, rtc >> - pl061, gpio >> - pci-host-generic >> - virtio_{mmio,pci,net,blk,scsi,console,balloon} >> - ext4 >> - DEBUG_BUGVERBOSE for debug purposes >> - neon, vfp extensions support (otherwise userland will fail with >> illegal instruction signal (code 0x00000004)) >> >> Signed-off-by: Yousong Zhou <yszhou4t...@gmail.com> >> --- >> I prepared this target initially only for the purposes of proper testing KVM >> support on Cubieboard2 as I cannot find an usable prebuilt binary on the net. >> >> It is posted as RFC because it will introduce a new target combination >> cortex-a15_neon and may place an extra burden on the build system of LEDE and >> the target users at the moment may be quite small. > > I started up initramfs image with qemu. And the /proc/cpuinfo stated: > Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt > vfpd32 lpae evtstrm > > So, wouldn't it make sense to change the > > CPU_SUBTYPE:=neon > > to > > CPU_SUBTYPE:=neon-vfpv4 > > Because, this way it will share the same "packages" with ipq806x. > So it will be less work for the phase2 builds. > > (Note: I haven't tested this with kvm on a A15, but only qemu-system-arm > on a x86). But I haven't seen any "illegal instruction signal (code > 0x00000004)" > there when I compiled a initramfs with neon-vfpv4. > > > Regards, > Christian
Yes, turning to neon-vfpv3 seems to be a fair trade-off as cortex-a15 is expected to have that feature on. The allwinner-a20 soc (dual-core cortex-a7) on cubieboard2 is also capable of neon-vfpv4 and I just assembled a small binary with ".fpu neon-vfpv4" from gas testsuite and it runs to end just fine with accel=kvm. It should also work with accel=tcg as qemu can provide the emulation. But I am not sure how it will work out with accel=kvm on a hardware without neon-vfpv4... I will provide a updated patch in the following days. yousong _______________________________________________ Lede-dev mailing list Lede-dev@lists.infradead.org http://lists.infradead.org/mailman/listinfo/lede-dev