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by xorcist 4303 days ago
Why on L4? Is Mill somehow tied to it, architecture-wise? Or is it just that L4 has a smaller footprint and is easier to port?
2 comments

Its about footprint. We certainly will run Linux on the Mill, but its work we don't have to put on the critical path. L4 is just a familiar lightweight OS, and we're keen to play with Mill-specific security features which are particularly applicable to microkernels too.

When we do port Linux, I expect it to become much more microkernel like, as in why would you want your disk drivers to be able to read write video memory etc?

> why would you want your disk drivers to be able to read write video memory etc?

That is a much bigger issue than the CPU architecture, as it has more to do with how the peripheral hardware works (firmware, DMA, etc.), but I appreciate the effort.

Well its how the CPU architecture exposes the hardware to software i.e. drivers. The Mill does MMIO but doesn't have rings.
Because the Mill has a single address space with memory protection, which works a lot better with L4 than it does with Linux. Porting Linux directly would probably be possible, but a huge effort the team wouldn't be able to pull off without a lot of extra resources.