erincandescent

Foreward

This document was originally written several years ago. At the time I was working as an execution core verification engineer at Arm. The following points are coloured heavily by working in and around the execution cores of various processors. Apply a pinch of salt; points contain varying degrees of opinion.

It is still my opinion that RISC-V could be much better designed; though I will also say that if I was building a 32 or 64-bit CPU today I'd likely implement the architecture to benefit from the existing tooling.

Mostly based upon the RISC-V ISA spec v2.0. Some updates have been made for v2.2

Original Foreword: Some Opinion

The RISC-V ISA has pursued minimalism to a fault. There is a large emphasis on minimizing instruction count, normalizing encoding, etc. This pursuit of minimalism has resulted in false orthogonalities (such as reusing the same instruction for branches, calls and returns) and a requirement for superfluous instructions which impacts code density both in terms of size and

erincandescent

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;

entity NibblerCPU is Port( 
   clk : in  STD_LOGIC;
   rst : in  STD_LOGIC;
   
   prog_addr : out std_logic_vector(11 downto 0);
   prog_data : in std_logic_vector(7 downto 0);

erincandescent

# dhcp server settings:
# dhcp-mac=set:rpi,b8:27:eb:*:*:*
# dhcp-boot=tag:rpi,boot,10.69.69.179

{ lib, stdenv, config, pkgs, ... }:
let
  alpineRelease = "3.11";
  alpineRevision = "2";
  alpineVersion = "${alpineRelease}.${alpineRevision}";
  

erincandescent

mkdir modloop-rpi
unsquashfs -d modloop-rpi/lib  ${alpinePiArmhf}/boot/modloop-rpi     'modules/*/modules.*' 'modules/*/kernel/net/packet/af_packet.ko'
(cd modloop-rpi  && find . | cpio -H newc -ov | gzip) > initramfs-ext-rpi
cat ${alpinePiArmhf}/boot/initramfs-rpi    initramfs-ext-rpi  > $out/initramfs-rpi

erincandescent

{1:F01AAAAGRA0AXXX0057000289}{2:O1030919010321BBBBGRA0AXXX00570001710103210920N}{3:{108:MT103 003 OF 045}{121:c8b66b47-2bd9-48fe-be90-93c2096f27d2}}{4:
:20:5387354
:23B:CRED
:23E:PHOB/20.527.19.60
:32A:000526USD1101,50
:33B:USD1121,50
:50K:FRANZ HOLZAPFEL GMBH
VIENNA
:52A:BKAUATWW
:59:723491524

erincandescent

Keybase proof

I hereby claim:

• I am erincandescent on github.
• I am erincandescent (https://keybase.io/erincandescent) on keybase.
• I have a public key ASDv23fqVwaH5NvQBQp0Y6Itt4lUspg2jfTc257yO_QGWAo

To claim this, I am signing this object:

erincandescent

>>> for x in socket.getaddrinfo("rei.local", None, socket.AF_INET6):
...     print(x)
...
(10, 1, 6, '', ('fe80::152:821e:3b05:9293', 0, 0, 0))
(10, 2, 17, '', ('fe80::152:821e:3b05:9293', 0, 0, 0))
(10, 3, 0, '', ('fe80::152:821e:3b05:9293', 0, 0, 0))
>>> for x in socket.getaddrinfo("rei.local", None, socket.AF_UNSPEC):
...     print(x)
...
(10, 1, 6, '', ('fe80::152:821e:3b05:9293%eth0', 0, 0, 2))

erincandescent

#![feature(custom_derive, plugin)]
#![plugin(serde_macros)]
extern crate serde;
extern crate serde_json;

#[derive(Serialize, Deserialize)]
struct S1 {
  a: Test,
  b: Test
}

erincandescent

#include <stdio.h>
#include <time.h>
#include <stdint.h>

__asm(
        ".align 16\n"
    "_overhead:\n"
        "mov 4(%esp), %eax\n"
        "mov $25, %ecx\n"
    "1:  dec %ecx\n"

erincandescent

echo *** Preparing for remote debug ***\n
target remote localhost:3333
set arm fallback-mode auto

define ifsr
  monitor arm mrc 15 0 5 0 1
end
define ifar
  monitor arm mrc 15 0 6 0 2
end