Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3

Ingo Molnar
2007-03-03T07:27:31Z

* Davide Libenzi <davidel@xmailserver.org> wrote:

> [...] Status word and control bits should not be changed from
> underneath userspace AFAIK. [...]

Note that the control bits do not just magically change during normal
FPU use. It's a bit like sys_setsid()/iopl/etc., it makes little sense
to change those per-thread anyway. This is a non-issue anyway - what is
important is that the big bulk of 512 (or more) bytes of FPU state /are/
callee-saved (both on 32-bit and on 64-bit), hence there's no need to
unlazy anything or to do expensive FPU state saves or other FPU juggling
around threadlet (or even syslet) use.

Ingo