Re: [9fans] Threads: Sewing badges of honor onto a Kernel

[Rob Pike <rob@mightycheese.com>]

this is a peculiar distortion of a peculiar episode.  the original
issue linus
objected to, and rather rudely if i remember right, is that if the
stacks are
distinct, there can be confusing bugs if you pass pointers around that
accidentally happen to refer to stack addresses.  in practice, we never
do this because the thread library makes it all but impossible.  however
this issue really rankled linus,

on the other hand, having a separate piece of address space with
different contents is a powerful idea.  it's called something like
per-thread space, and it's really convenient for many implementation
details in threading.  but the feature is (or was; i really don't know
the
situation any more) hard to provide on linux and in fact the clone
interface used to be really nasty because the two processes returned
from the syscall with two processes sharing the same stack.  i
understand
something has been done to make the code after a clone on linux
easier to write, but when linus was dyspeptic about rfork, the linux
dance was really tricky.

so it's just a detail, a design choice with advantages and disadvantages
either way.  win some, lose some. yet somehow our code
is 'stupid' and linux is 'proper', so i guess the snarkiness endures.

-rob