Re: [MiNT] XaAES / GEM memory issues

[Sven Karlsson <svenka@it.kth.se>]

Hi Konrad,

> Please tell me, why clipping and window locations have to be integrated to
> the kernel (whatever way it is done, i assume an XDD).

Yes, it is as a XDD in MiNTs case.

The reason is simple. The device driver will be opened by several
processes at once and the device driver code must decide which process
that should get the event and you need the windowlist and in practice
the cliprectangles for that. It is pointless to add another level, i.e.,
the AES, just to multiplex the events. It would only get you more
overhead. 

I cannot recall if MiNT allows one device driver to be opened multiple
times by different processes but this shouldn't be hard to implement
into the kernel. It should only be a flag set by the device driver when
it is loaded... It could also potentially be beneficial in other areas,
eg. scsi/ide lowlevel drivers where you might want specific applications
like Direct-2-Disc audio software or databases to access a separate raw
partition using the same drivers as the filesystems. The device driver
must of course be aware of this and restrict the usage so that several
processes access the same partition at once.
 
> > All suggestions so far all in some way suggests using special mouse or
> > keyboard device drivers. I cannot see the difference.
> 
> Well, I can see. Incorporating parts of AES and VDI into the kernel you
> make the kernel designed especially to be used with AES and VDI. We
> _don't_ want that.

Agreed. But in my world and also in most texts about OSes device drivers
are a part of the kernel. If you write a device driver you integrate
some functionality into the kernel. I'm not proposing alterations to the
kernel. I'm proposing a device driver and that would be a part of the
kernel.

(Footnote: Exo and micro kernels are no exception but you have to extend
the kernel to mean kernel level servers as well. I have worked to much
with exos ans micros that I'm damaged I supposed. In my world a server
in kernel mode is quite the same thing as a device driver.)

Best regards
 Sven