CODEWITHSUNDEEP
c++cassemblyconcurrencynative
user2889419
user2889419

Reputation:

Multithreading at boot time?

We are developing a very low-level app-system which runs before OS boot, in-fact a boot application.
the question is how we should utilize CPU cores/threads?
And how many thread we would run?
Is it possible at all?! is there any link/tutorial?

Upvotes: 3

Views: 583

Answers (1)

Anonymous
Anonymous

Reputation: 431

Since you're talking about threading before booting the OS, I'm going to assume that no kernel is available to you yet. That means no system calls, so no fork() or clone(). For the purpose of this answer, however, I'm also going to assume that you have already set up the A20-gate, a GDT, either protected (for IA-32) or long (for x86-64) mode, and so on. If you don't know what these are, we probably shouldn't be talking about threads before booting to begin with.

There are opcodes and tricks you can use to let your processor use other cores, thus implementing threading quite directly. You can find all these things in the Intel x86 (you are working on x86, are you? You obviously need a different set of manuals if you're on a different architecture) manuals here: http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-manual-325462.pdf

The reason there are no tutorials for something like this is, quite frankly, that it's not very useful. The entire point of setting things up before loading the kernel into memory is to make it easier to load the kernel into memory. Threading does not exactly contribute to this goal. It would be advisable to simply let the kernel deal with such low-level implementation requirements, so that you can then use the fork() and clone() system calls for all your threading needs.

EDIT: Good correction by Sinn: fork() create a new process, which of course isn't actually threading.

Upvotes: 12

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