Re: [9front] [PATH] error()/waserror() for userspace

[cinap_lenrek@felloff.net]

Some notes and questions:

1)
privmalloc() should probably round the size up to 8 bytes,
so we maintain struct alignment.

2)
We need a manpage for privmalloc() describing the zeroing
semantics on fork().

3)
Should privmalloc() nil instead of abort()? arguments pro/con?

4)
maybe should introduce privmalloc() as a separate commit.
this has alot of impact as you'd want to implement nsec()
and atexit() using this new mechanism. doing that first
is a way to ensure that the design is sound. also, we
have to think about backwards compaty. if you run a old
kernel that has no "private" segment trype. should atexit()
fall back on global pid tagged array? ect.

5)
theres no range check in pusherrlab(). It just silentely
corrupts memory.

6)
Maybe call Errlab to "Errlabs" because it represents multiple
error labels. In the kernel, we have Label struct representing
a single "jumpbuf" and it is put in the Proc struct as Label
errlab[NERR].

7)
Is 32 labels good enougth? For libthread, we could even
just allocate the labels dynamically as we control the
whole thread. a jmp_buf costs you like 16 bytes, which
means the thread gets bloated by 512 bytes, even if
we never use error().

8)
For porting programs using privmalloc(), how'd we be able
to emulate these semantics? Is it possible?

9)
Should we provide a noteerror(ureg) function,
so you can raise an error from a note handler?

--
cinap