Are there any models of operating systems which don’t require rings of privileges, that are also secure?

I am working on a simple operating system in JavaScript and have noticed that there are two kinds of processes: the “main” process (or “kernel” process), and all the other processes. Basically they are implemented completely differently (which makes sense). But I’m wondering if you could reuse some of the logic and just have it all be one type of process. Do any operating systems do this? If so, what do they do? If not, why not?

Why are more and more websites increasingly operating subscription models?

[No idea if this is the right community so please forgive if not]

More and more I am noticing websites charging for subscription services, whereas years and years ago I suppose when less data was being sent and received [in the days of lower speeds etc.] most websites were free. Youtube is a particular example – now they are offering Youtube Premium whilst introducing inconveniences for free users. Amazon makes less sense to me as surely they profit enough serving as a shopfront, but they have also introduced features such as Amazon Prime.

Apart from the obvious – because who doesn’t want to make a profit – why is this? I would be interested to get some insight from people knowledgeable about this kind of thing as I am only a user and can only guess.

How to run 64bit software on 32bit operating system?

I have a Windows software that only has 64bit version and I want to run it on my linux computer. I know I can use wine on linux but my OS is 32bit and my hardware supports 64bit I know that I can run a 64bit program on a 32bit operating system using a virtual machine but I don’t know how to do it. I hope someone will show me how to do it.

Why to disable McAfee Antivirus before updating Operating System to windows 10? – McAfee Antivirus

The reason why one should disable McAfee before updating operating system to windows 10 is that it might get the software into compatibility issues and can thus corrupt the system functioning and also the antivirus, therefore, it is necessary to get the software disabled while updating the operating system to windows 10. If you still need more help or support then, in that case, connect with the team of trained and certified experts.

http://www.mcafee.support-numbers.co.uk

Do modern operating systems still send targeted or directed Wi-Fi probe requests that contain SSIDs?

Do modern (versions of) operating systems, primarily Android and iOS on mobile, still send targeted or directed probe requests when searching for Wi-Fi networks to connect to?

Such targeted or directed probe requests contain the SSIDs of known networks, and may thus leak information about the sending device’s location history, the owner’s social relationships, etc.

According to this source, modern operating systems do not send these requests anymore:

Around 2014, the privacy implications of targeted probe requests started to become widely publicized and understood. Most new devices therefore stopped sending them. […] When the privacy implications of targeted request probes became widely appreciated, most new mobile devices stopped sending them altogether. […] Targeted probe requests are mostly a thing of the past.

Other sources, like this one or this one, seem to confirm that targeted probe requests are not sent anymore on the latest versions of Android, at least.

If this is indeed true, and perhaps also for iOS (and some desktop OSs), are there any press releases, bug tracker entries, security reports or code commits that confirm this?

Directed probe requests, as opposed to broadcast requests that don’t contain a network’s SSID, should only be necessary for hidden networks. The impact is stronger on mobile devices, where you tend to both have more known networks added to your device and broadcast that list in more places.

How many segments a process can have in operating system employing Segmentation for memory management

Some facts about “Segmented Paging”

1) Each process has one segment table.
2) There is one-page table per segment.

Fact about “Paged segmentation”

3) Contains page table of segment table.

Now consider following problem

In a paged segmented scheme of memory management, the segment table itself must have a page table because. (A) The segment table is often too large to fit in one page.
(B) Each segment is spread over a number of pages.
(C) Segment tables point to page tables and not to the physical locations of the segment.
(D) The processor’s description base register points to a page table

Given solution is:

Here option (A) is true , as segment table are sometimes too large to keep in one pages. So, segment table divided into pages. Thus page table for each Segment Table pages are created.

My Doubt

I believe a page can contain several hundreds of segment table entries of form

  <segment base, limit> 

I only came across code, data, stack and heap segments. I believe a process can have only these “four” segments. And also, we know each process has a segment table (Fact 1). Then how a segment table can grow so large that it cannot be fitted in a single page?