Re: [PATCH v10] lib: checksum: Use aligned accesses for ip_fast_csum and csum_ipv6_magic tests

[Guenter Roeck <linux@roeck-us.net>]

On 2/27/24 14:44, David Laight wrote:
> ..
>> This is the "known" list of failures. I don't currently run kunit tests
>> on nios2 or riscv32, for example, nor on any architectures with no qemu
>> support.
> 
> nios2 is definitely going to 'crash and burn' if you do a misaligned access.
> 

Curiously enough, it doesn't. I get lots of

kernel unaligned access @ 0xc848eb78; BADADDR 0xc86f1d01; cause=6, isn=0x20800017

but a checksum test with unaligned data does pass, so the kernel
somehow handles it. It does crash, later, though, if CONFIG_NET_TEST
is enabled. Apparently the gso tests trigger lots of unaligned
accesses, and those are just too much for the kernel to handle.

Guenter

> Although Intel (aka the Altera bit) are claiming current version
> of their Quartus fpga build software is the last one the will
> support the nios2.
> They are expecting everyone to move to a risc-v soft cpu instead.
> We aren't happy about that, I doubt some of the big telco's are
> either - I believe some mobile base stations have fpga with a
> lot of nios2 in them - almost certainly running with a few kB
> of code and data memory and running small control tasks.
> If you want to run Linux, find an fpga with an ARM core.
> 
> There are some solutions - like writing a compatible soft cpu.
> 
> 	David
> 
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