Re: QEMU PIC indirection patch for in-kernel APIC work

Ingo Molnar
2007-04-04T21:21:03Z

* Anthony Liguori <aliguori-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> wrote:

> But why is it a good thing to do PV drivers in the kernel? You lose
> flexibility and functionality to gain performance. [...]

in Linux a kernel-space network driver can still be tunneled over
user-space code, and hence you can add arbitrary add-on functionality
(and thus have flexibility), without slowing down the common case (which
would be to tunnel the guest's network traffic into the firewall rules
of the kernel. No need to touch user-space for any of that).

if performance didnt matter and if it were all about flexibility then
Bochs/Qemu could have migrated most Windows users to Linux 10 years ago.
The reality is, performance and precision of emulation very much
matters.

Ingo