[LEDE-DEV] [RFC] target: armvirt: new target

[Christian Lamparter]

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 <yszhou4tech at 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