Re: Major GNU/Hurd using report
On Thu, May 04, 2000 at 01:39:50PM +0300, Kalle Olavi Niemitalo wrote:
> Tomasz Wegrzanowski <maniek@beer.com> writes:
>
> > Therefore there are these possibile reasons, why it is possible to r/w hardware ports :
> > - I/O Permision Level is way too low
> > but asm(pushfl) says IOPL=0 (kernel only)
> > - user programs run in kernel space
> > I hope not, no test was done
>
> This could be seen from the lowest bits of CS (as you probably know).
%cs & 0x03 = 0x03
fortunately user-space
> > - Mach gives default permision to every program to use all hardware ports
> > No test was done yet
>
> Or:
> - the processors traps the instructions, but Mach's exception
> handler lets them run anyway
Any of these two, if Mach allows us to make userspace drivers
is seems to be good idea to put all auxiliary device support
(sound cards, graphics) in user-space.
KGI is quite portable (some parts needs to be non-preemptive, possible on Mach ?)
Probably IRQ manager should been put into Mach.
It should also export pci configuration to user space (?)
> Mach actually has code to detect the first access to a port and
> set the flag in the bitmap if permitted. Could you add some
> printfs in gnumach/i386/i386/io_emulate.c and
> gnumach/i386/i386at/iopl.c?
I'm not going to try compiling gnumach in *near* term.
I had enough bad experience with Linux 2.3
and am affraid of kernels since then.
BTW : what about idea, that mach should save all booting messages
into RAM and then redirect it to userspace ?
Due to lack of Linux-like scrool-back it is difficult to read them.
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