40 ms·

Why do you trust the assembler you got from somewhere any more than a compiler?

by drfuchs 4y ago

randyrand 4y ago
Because hand written assembly is readable!
- chongli 4y ago
  I believe GP used assembler to refer to the program which reads your hand-written assembly and produces a binary. That program was presumably given to you so you need to trust it. No, the only way to solve this problem is to start with a computer entirely devoid of code and bit-bang your assembler into the machine with switches, the way the first users of the MITS Altair did it.
  - ByteJockey 4y ago
    You can also bootstrap the way lisp did and write the fist compiler in the language and get a bunch of grad students to hand-compile it. But, yeah if you don't have a bunch of grad students at the ready, an assembler hand-written in machine code is the only option if you want to trust the entire stack. Though I'm not sure what that would get you. I don't know of any higher language compilers that are written directly in assembly these days, so you'd never be able to compile your C/C++ compiler.
    - chongli 4y ago
      There was a C compiler written in assembly posted on HN 4 years ago [1]! So yeah, if you wanted to, you could bit-bang an assembler capable of assembling a simple C compiler, then in your simple subset of C you could implement a full C compiler, and from there you can do anything you want! The grad student approach also sounds interesting. A basic Lisp interpreter can easily fit on a single letter-sized sheet of paper. A single person could hand-compile that, it would just take longer. But, if you're living alone in a cabin in the woods with your own hand-built computer and a personal library of computer books in hard copy, that would be a totally feasible project. [1] https://news.ycombinator.com/item?id=17851311 https://news.ycombinator.com/item?id=17851311
      - ByteJockey 4y ago
        I wasn't aware that there were any existing C compilers made in asm for modern architectures. I guess I shouldn't be too surprised. That's cool, thanks for showing me.
- pjmlp 4y ago
  It might be, but have you also validated the microcode executing it? Or the Verilog/VHDL for the logic gates used by the CPU, for that matter?
  - randyrand 4y ago
    Security is multifaceted. Ideally, yes. But you still will be more secure than having multiple security holes.

Why do you trust the assembler you got from somewhere any more than a compiler?

randyrand 4y ago

Because hand written assembly is readable!

chongli 4y ago
I believe GP used assembler to refer to the program which reads your hand-written assembly and produces a binary. That program was presumably given to you so you need to trust it. No, the only way to solve this problem is to start with a computer entirely devoid of code and bit-bang your assembler into the machine with switches, the way the first users of the MITS Altair did it.
- ByteJockey 4y ago
  You can also bootstrap the way lisp did and write the fist compiler in the language and get a bunch of grad students to hand-compile it. But, yeah if you don't have a bunch of grad students at the ready, an assembler hand-written in machine code is the only option if you want to trust the entire stack. Though I'm not sure what that would get you. I don't know of any higher language compilers that are written directly in assembly these days, so you'd never be able to compile your C/C++ compiler.
  - chongli 4y ago
    There was a C compiler written in assembly posted on HN 4 years ago [1]! So yeah, if you wanted to, you could bit-bang an assembler capable of assembling a simple C compiler, then in your simple subset of C you could implement a full C compiler, and from there you can do anything you want! The grad student approach also sounds interesting. A basic Lisp interpreter can easily fit on a single letter-sized sheet of paper. A single person could hand-compile that, it would just take longer. But, if you're living alone in a cabin in the woods with your own hand-built computer and a personal library of computer books in hard copy, that would be a totally feasible project. [1] https://news.ycombinator.com/item?id=17851311 https://news.ycombinator.com/item?id=17851311
    - ByteJockey 4y ago
      I wasn't aware that there were any existing C compilers made in asm for modern architectures. I guess I shouldn't be too surprised. That's cool, thanks for showing me.
pjmlp 4y ago
It might be, but have you also validated the microcode executing it? Or the Verilog/VHDL for the logic gates used by the CPU, for that matter?
- randyrand 4y ago
  Security is multifaceted. Ideally, yes. But you still will be more secure than having multiple security holes.