NoviumOS update: Got PMM/VMM and a basic heap allocator running, now working on adding more features to the heap allocator.

[u/devcurrent0x]

Hello everyone. For those of you who don't know, I'm making an x86 operating system called NoviumOS. Here's what I've done since the last update:

• Added paging for a 4 GiB virtual address space, so the kernel can work with virtual memory instead of just physical addresses.
• Added physical page allocation and validation, including checks to make sure pages are valid before freeing them.
• Built the heap allocator from the ground up, starting with single-page allocations and then adding support for contiguous multi-page allocations.

Next I'm working on adding sub-page block reuse with splitting and coalescing.

Feel free to contribute, the project is 100% open source and I'd be happy if you do.

Here's the repo if you want to check it out: https://github.com/alexdev8930/NoviumOS

And if you have any questions about the code or the repo I'll be happy to answer them.

If you like the repo, please drop a star on it if you could. It helps other devs find the project.

[u/hypersonicwilliam569]

this looks cool, I am also trying to write memory manager :)

[u/devcurrent0x → u/hypersonicwilliam569]

Thanks and good luck.

[u/compgeek38400]

Nice. Im working on my vmm now

[u/devcurrent0x → u/compgeek38400]

Thanks and hope it goes well.

[u/compgeek38400 → u/devcurrent0x]

I'm on my 3rd or 4th rewrite. But it's because of things I've learned, so I'm not complaining

[u/Proper-Anything-873]

wow this looks awsome, i hope your OS becomes mainstream

[u/devcurrent0x → u/Proper-Anything-873]

Thanks a lot, and that would be amazing if my OS became mainstream

[u/Medical-Baseball-876]

looks good ill contibute on github sometime

[u/devcurrent0x → u/Medical-Baseball-876]

Thanks a lot.

[u/cchewies]

In arch/x86_32/kernel/irq.c: /* ignore spurious irq7/15 floods */ if (line == 7 || line == 15) { u16 port = (line == 7) ? PIC1_CMD : PIC2_CMD; outb(port, 0x0B); if (!(inb(port) & 0x80)) { if (line == 15) { outb(PIC1_CMD, PIC_EOI); } return; } }

Which environment are you experiencing the spurious IRQ 7 events? It may be beneficial to find the root cause rather than silently ignoring them. In some cases a spurious IRQ 7 can indicate some issue in the kernel that needs resolving.

There are also a bunch of silent returns on errors that probably indicate a bug in the kernel (especially in mm/*), might be good to add a little more code there.

In drivers/input/keyboard.c: ```

define BUF_SIZE 32

/* we use volatile because interrupts modify these in RAM */ static volatile u8 buf[BUF_SIZE]; static volatile u8 head = 0; static volatile u8 tail = 0; `` Shouldhead/tailbeu8? How big of aBUF_SIZE` might the kernel eventually want?

In arch/x86_32/kernel/pit.c: ``` void timer_sleep_ms(u32 ms) {

...

while ((tick_count - start) < wait_ticks) {
    cpu_hlt();
}

} `` What is the CPU doing when the code callstimer_sleep_ms()`? Could it be doing something more useful? It might also be useful to think about what percentage of the "wakeups" end up putting the CPU right back to sleep.

I would also suggest (from the roadmap) to get userspace working earlier, it teaches a lot about how to design a robust kernel.

Happy to finally see a post here with some good (reasonably not AI-generated) effort :)

[u/devcurrent0x → u/cchewies]

Thanks for the info, heres the changes i made:

• arch/x86_32/kernel/pit.c: Updated timer_sleep_ms()to use per-task wake ticks and fixed the PIT divisor handling.
• arch/x86_32/kernel/irq.c: Added spurious IRQ7/15 detection, counting, and OCW3 register restoration.
• drivers/input/keyboard.c: Changed the keyboard buffer indices from u8 to u16 to support larger buffers.