Date: Tue, 23 May 2017 09:04:40 +0530 From: Shubham Bansal <illusionist.neo@...il.com> To: Florian Fainelli <f.fainelli@...il.com> Cc: Kees Cook <keescook@...omium.org>, Daniel Borkmann <daniel@...earbox.net>, "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Network Development <netdev@...r.kernel.org>, ast@...com, Mircea Gherzan <mgherzan@...il.com>, David Miller <davem@...emloft.net>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, nschichan@...ebox.fr, andrew@...n.ch Subject: Re: arch: arm: bpf: Converting cBPF to eBPF for arm 32 bit Hi Florian, >> I think it is fine to only target ARMv7. It is harder and harder to >> find devices on v5 or v6 CPUs that would want to be using BPF JIT, >> IMO. > > There are still a ton of Marvell-based routers out there (e.g: Kirkwood, > Orion5x) that are ARMv5 and that prompted Nicholas (hey there) to fix > the cBPF JIT a while ago. I don't think you can just ignore those, it's > fine not to target them initially, but arguably, QEMU has decent support > for some ARMv5 platforms that could be used for testing as well > (realview-eb, versatileab/pbm. I am using busybox to get the rootfs. Here is what I am doing :- 1. ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- make -j4 (for kernel build as well as busybox build) 2. qemu-system-arm -M vexpress-a9 -dtb ./linux/arch/arm/boot/dts/versatile-ab.dts -kernel ./linux/arch/a rm/boot/zImage -append "root=/dev/mmcblk0 console=ttyAMA0" -sd ./a9rootfs.ext3 --nographic Can you help me with running qemu for ARMv5 and ARMv6 ? >> When they "disappear", it's because there isn't a prerequisite met. I >> either read the Kconfig files or use "make menuconfig" and "search" to >> tell me where a config is defined and what is needed to meet the >> prerequisites. >> >> In the case of CPU_BIG_ENDIAN, you need ARCH_SUPPORTS_BIG_ENDIAN, >> which appears to be only ARCH_IXP4XX. I don't think you're going to >> find an emulator that will handle this, so I'd suggest ignoring this >> config for now unless you can find someone with that hardware that you >> can work with to test it. >> >> In the case of CONFIG_FRAME_POINTER, I assume you built a >> THUMB2_KERNEL? I'd read the notes in arch/arm/Kconfig.debug for >> 'config FRAME_POINTER'. > > It sounds like we are at the point where Shubham's patches should be > posted so people could test/fix on earlier ARM devices for instance. > I would post them as soon as I test them on ARMv5 and ARMv6. If you can help me with that, please let me know. > Thanks > -- > Florian -Shubham
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