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| What should be implemented before multitasking? https://forum.osdev.org/viewtopic.php?f=15&t=36760 |
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| Author: | mrjbom [ Thu May 14, 2020 1:31 pm ] |
| Post subject: | What should be implemented before multitasking? |
Hi. I want to implement multitasking in my OS, but I don't understand what I need to do before that. Now I can work work with the keyboard and I have a primitive physical memory manager (divides the memory into pages and allocate the desired number of pages), is this enough to implement kernel multitasking? Or should I do something else? I think so, but it's better to ask. |
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| Author: | AndrewAPrice [ Thu May 14, 2020 5:57 pm ] |
| Post subject: | Re: What should be implemented before multitasking? |
Very close, you just need to implement interrupt handling. Return from the interrupt with a different set of registers (including the instruction pointer and stack pointer) to what you entered with. Then, this interrupt could be fired from a timer or manually fired by a thread willing to give up control. |
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| Author: | iansjack [ Fri May 15, 2020 12:52 am ] |
| Post subject: | Re: What should be implemented before multitasking? |
I'd say that allocating memory as pages, rather than smaller amounts, is going to be a little wasteful. I'd recommend writing a memory allocator to hand out smaller chunks of (virtual) memory. |
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| Author: | mrjbom [ Fri May 15, 2020 8:26 am ] |
| Post subject: | Re: What should be implemented before multitasking? |
AndrewAPrice wrote: Very close, you just need to implement interrupt handling. Return from the interrupt with a different set of registers (including the instruction pointer and stack pointer) to what you entered with. Then, this interrupt could be fired from a timer or manually fired by a thread willing to give up control. I already have interrupts, I think I need to implement software interrupts somehow. I also need a timer with millisecond accuracy to switch between tasks. But I don't know what kind of watch will help me. |
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| Author: | AndrewAPrice [ Fri May 15, 2020 1:31 pm ] |
| Post subject: | Re: What should be implemented before multitasking? |
I found the PIT very easy to use. It'll fire an interrupt on IRQ0. |
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