Re: [9fans] FreeBSD 4.0 / Plan9 3rd ed.

[Alexander Viro <viro@math.psu.edu>]

On Fri, 1 Sep 2000, Russ Cox wrote:

> The Linux drawterm will not work
> in most other places, even under 
> binary emulation, because it depends
> on the task segment selector as
> a unique thread id.  This is the same

Sorry? "other places" include 2.4, for one thing. Why using gross
architecture-dependent tricks, when PID is there? On Linux
thread==process. There is a rfork() equivalent (clone(2)) and model is
exactly the same as on Plan 9 (process as a set of components that can be
shared between several processes; fork() as a special case of more generic
operation that copies a subset of components and uses the old ones for the
rest, etc.)

Use of TSS happened to work on x86 prior to 2.3.11 or so, but that relied
on the details of task_struct allocation. 2.4 has TSS-per-CPU  setup and
doesn't bother with changing the register at all - it's cheaper to do
everything by hands. Besides, it lifts the limit on number of processes
and allows to avoid quite a few TLB flushes.

Use getpid() - it's at least more portable than %tss and definitely much
saner.

> reason that the Inferno Linux binaries
> don't work under other OSes with
> Linux binary emulation.

Ditto.