On 5/20/23, William ML Leslie <william.leslie....@gmail.com> wrote: > Hello, > > I just noticed in the new x86-S rfc that Intel published that there will be > no further support for io port access for processes in ring 3. Thankfully, > this doesn't look like it will impact seL4, which provides capabilities to > special objects representing port ranges on x86, which are then implemented > in the kernel. Just in case anyone was wondering if there will be any > impact, since this is the one thing that stuck out to me. >
I'd actually thought of trying to add support for direct use of PMIO instructions in user code under seL4 at one point, but there's probably not much of a point in that because modern performance-critical devices most often use just MMIO only. Really I'm not sure why Intel wouldn't just do away with PMIO entirely and just map ports onto MMIO (like on non-x86 architectures with PCI-like buses) if they're trying to clean up legacy cruft. Another thing that would be an issue is the 32-bit boot code. I have preliminary code in my custom Multiboot loader for loading a 64-bit kernel directly into long mode, but I only ever used it with earlier experiments and never with seL4. I have disabled the ELF32 kernel conversion in my OS since my loader supports ELF64 binaries even though only 32-bit entry is working with seL4. Of course, my loader works rather differently than the CAmkES/seL4CP one does (the image is a list of separate Multiboot modules, one per file, rather than a cpio archive linked into the root server), so it wouldn't necessarily be a replacement. _______________________________________________ Devel mailing list -- devel@sel4.systems To unsubscribe send an email to devel-leave@sel4.systems
