Re: Making Lemonade (Floating-point format changes)

BGB wrote:

On 5/13/2024 6:25 PM, MitchAlsup1 wrote:

 

Also (in my case):
Debugging is rather annoying in cases where dealing with bugs appear/disappear/move around at random or with the slightest perturbation...

 You need better verification--Oh Wait ...
 

Not sure I understand what you mean by this.

Some of these bugs are behaving very similar to some bugs I was battling against a while ago (but never properly debugged, the bug just sort of seemingly disappeared).

What you need is 1M-1B instructions that test every known corner case
so if a fix breaks something else you will find it almost instantaneously.
{At 50 MHz 1B instructions is 50 seconds of run time.}
In the semiconductor industry, we use this test suite in the simulators,
emulators, on the test head, and on parts returned from the field. Also,
it is under constant evolution simply so we don't let corner cases let
bugs into sellable parts.

Also I may need to rework how page-in/page-out is handled (and or how IO is handled in general) since if a page swap needs to happen while IO is already in progress (such as a page-miss in the system-call process), at present, the OS is dead in the water (one can't access the SDcard in the middle of a different access to the SDcard).

 Having a HyperVisor helps a lot here, with HV taking the page faults
of the OS page fault handler.

Seems like adding another layer couldn't help with this, unless it also abstracts away the SDcard interface.

With a HV, GuestOS does not "do" IO is paravirtualizes it via HV.
So, having a GuestOS in a position it cannot deal with another page
fault is no longer a hindrance:: GuestOS does not see that page fault;
it is just handled and goes away.