[Info-vax] Intel proposal to simplify x86-64

[Johnny Billquist]

On 2023-06-07 14:16, Simon Clubley wrote:
> On 2023-06-07, Johnny Billquist <bqt at softjar.se> wrote:
>>
>> Well. If you want full isolation between different parts of the kernel,
>> going fully microkernel and message passing and all that, it's perfectly
>> doable on pretty much any hardware. It's just that in general, whenever
>> it has been done, performance always suffer. Which is why pretty much
>> noone is doing it. And it's not because of issues in the hardware that
>> it suffers. It's just that you can't avoid a lot more overhead when
>> doing things this way. A lot of data copying first and foremost.
>>
> 
> QNX.

Good point. There are a few more implementations, indeed.

>> I guess Honeywell did, but can't say they were overly successful. MACH
>> also did, but that part seems to not live on anywhere.
>>
> 
> We have long moved past the point where absolute speed is the primary
> driver in software design. Today, the focus should be on safer computing,
> even at the expense of some overhead. To do otherwise is utterly
> irresponsible in today's world IMHO.

You might think so, and argue for that. Seems most other people are 
disagreeing, even to the point of QNX slightly moving away from it for 
performance reasons. To quote wikipedia:

"All I/O operations, file system operations, and network operations were 
meant to work through this mechanism, and the data transferred was 
copied during message passing. Later versions of QNX reduce the number 
of separate processes and integrate the network stack and other function 
blocks into single applications for performance reasons."

> BTW, note that I said "safer" computing. I did not say "safe" computing.
> 
> There is no such thing as absolutely safe computing, especially when the
> attacker is determined enough and resourced enough. The goal is to put
> enough barriers in the way of most attackers that they cannot achieve
> their goals and to make it expensive and painful for those attackers
> who work for nation state authorities.

True...

   Johnny