commit ac09572db0e618d9575da411b3c7b81b7818d233
parent a5673fcc973d3546dd4335bb0508a29aaaa0900b
Author: Virgil Dupras <hsoft@hardcoded.net>
Date: Wed, 20 Jul 2022 15:17:42 -0400
doc: lib or sys?
Diffstat:
1 file changed, 32 insertions(+), 0 deletions(-)
diff --git a/fs/doc/arch.txt b/fs/doc/arch.txt
@@ -109,3 +109,35 @@ A typical system will spit a prompt and pass the control to /sys/rdln, which
reads input line by line and interprets them.
The system is yours.
+
+# lib or sys?
+
+What's in /lib? What's in /sys? This question can sometimes lead to confusion.
+
+/lib is for "libraries", a set of mostly stateless logic. /sys is for
+subsystems, also a set of logic, but often stateful, centered around one or
+more resources.
+
+Libraries will typically be loaded by apps, subsystems and other libraries with
+the help of ?f<< (load file if it's not already loaded).
+
+Subsystems will be loaded during init.fs. If a unit requires the subsystem, it
+will indicate it with "require", which doesn't load anything, but errors out if
+the unit isn't loaded.
+
+Sometimes, the line between the two is fuzzy. These questions will help draw
+the line.
+
+1. Who will decide when we want to load it, the system operator or the
+application writer? If it's the sysop, it's a subsystem.
+
+For example, some applications might needs some words from sys/rdln, but it
+doesn't make sense to automatically load it when needed: if the sysop hasn't
+specifically decided to load it in its system, this dependency has a lot of
+chances to be nonsensical.
+
+2. Is the unit centered around a resource that needs configuration? If yes, it's
+a subsystem.
+
+For example, sys/scratch is centered around a buffer which can vary in size
+depending on what the sysop wants.
