Illegal instruction in init when trying to run Linux

[Kimplul]

Hi, I'm trying to follow the instructions for running Linux on an Arty A7 35T, but the kernel panics with

[    1.765358] init[1]: illegal instruction (4) at 3fffb08366d4 nip 3fffb08366d4 lr 3fffb0828b74 code 1 in ld64.so.2[3fffb07f5000+51000]
[    1.778216] init[1]: code: 00000000 000c2040 00000010 735f0007 6d6a7465 00000070 3c4c0003 38426744
[    1.787716] init[1]: code: f8230000 7c0802a6 f8430008 f9c30018 <d9c300b0> f8030010 f9e30020 d9e300b8
[    1.797633] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004

I'm using microwatt commit fdcb6ec, Linux commit torvalds/linux@7a39682 and buildroot commit shenki/buildroot@b256b00.

[mikey]

It fails because you don't have floating point.

The failing instruction is 0xd9c300b0 which a floating point instruction (stfd. f14, 0xb0(r3)).

The build you are using (A7 35T) doesn't have floating point because that device is too small to contain it.
https://github.com/antonblanchard/microwatt/blob/master/microwatt.core#L306

You either need to recompile your buildroot without floating point, or upgrade to the 100T so you can fit the floating point unit.