f4f4caab0e
I wanted a tiny scriptable meltdown proof way to run userspace programs and visualize how program execution impacts memory. It helps to explain how things like Actually Portable Executable works. It can show you how the GCC generated code is going about manipulating matrices and more. I didn't feel fully comfortable with Qemu and Bochs because I'm not smart enough to understand them. I wanted something like gVisor but with much stronger levels of assurances. I wanted a single binary that'll run, on all major operating systems with an embedded GPL barrier ZIP filesystem that is tiny enough to transpile to JavaScript and run in browsers too. https://justine.storage.googleapis.com/emulator625.mp4 |
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| .. | ||
| calls | ||
| consts | ||
| errfuns | ||
| machcalls | ||
| stubs | ||
| README.md | ||
| consensus.py | ||
| consts.sh | ||
| errfuns.h | ||
| errfuns.sh | ||
| g_syscount.S | ||
| gen.sh | ||
| machcalls.sh | ||
| macros.h | ||
| restorert.S | ||
| syscall.S | ||
| syscalls.sh | ||
| systemfive.S | ||
| sysv.mk | ||
| versions.txt | ||
README.md
SYNOPSIS
System Five Import Libraries
OVERVIEW
Bell System Five is the umbrella term we use to describe Linux, FreeBSD, OpenBSD, and Mac OS X which all have nearly-identical application binary interfaces that stood the test of time, having definitions nearly the same as those of AT&T back in the 1980's.
Cosmopolitan aims to help you build apps that can endure over the course of decades, just like these systems have: without needing to lift a finger for maintenance churn, broken builds, broken hearts.
The challenge to System V binary compatibility basically boils down to numbers. All these systems agree on what services are provided, but tend to grant them wildly different numbers.
We address this by putting all the numbers in a couple big shell scripts, ask the GNU Assembler to encode them into binaries using an efficient LEB128 encoding, unpacked by _init(), and ref'd via extern const. It gives us good debuggability, and any costs are gained back by fewer branches in wrapper functions.z