[LLVMdev] an OS around LLVM
mindmachine at free.fr
mindmachine at free.fr
Sun Jan 26 07:04:10 PST 2014
Thanks a lot for this information, that helps! I'll have a close look at SVA.
Currently, I plan to use asm.js as portable low-level language, but that might
change in the future. I made this choice after reading:
By the way, my project is no longer an OS. It's now a desktop environment. The
new address of my project is:
Again, thanks for replying.
Selon John Criswell <criswell at illinois.edu>:
> On 12/17/13 8:03 AM, mindmachine at free.fr wrote:
> > Hi all,
> > If it's not the right place to ask, please forgive me.
> > Currently I'm working on a new operating system concept, called "Om".
> > The first feature would be Android-like apps, coming in *.opk files that
> > contain all needed resources and source-code expressed in LLVM-IR assembly
> > language.
> > http://sett.com/openminded-os/uid/88508
> > How does it sound ?
> I've seen several suggestions made on this thread on topics related to
> what you want to do. To be honest, I don't really have a good idea what
> your goal is, and I didn't have sufficient patience to wade through your
> blog to find out. As a suggestion for the future, you should describe
> your goal or goals more specifically in the email to the list.
> What you need really depends on what your goals are. If you want some
> sort of language in which application code is represented so that it is
> portable across difference architectures, then I think LLVM would be a
> good choice. That said, there are several issues that LLVM doesn't deal
> with that you would need to address. The biggest one is
> architecture-specific details that are exposed in source-languages like
> C/C++ and are often encoded in the TargetData information within an LLVM
> IR bitcode file. Examples include pointer size, endianness, memory
> alignment requirements, etc. Note also that you'll have to deal with
> how these details are exposed at the source language level. Languages
> like C make these details visible, so the programmer can write
> non-portable code. Languages like Java can keep these details hidden,
> allowing Java programs to be much more portable.
> I believe the PNaCL work addresses some of these issues.
> If you want *everything,* include the OS kernel, to be represented in
> LLVM IR, then you should take a look at the LLVA/SVA work. In that
> work, we removed the inline assembly code in the OS and replaced it with
> high-level instructions that we (logically) added to the LLVM
> instruction set. It still isn't portable in the way that PNaCL is, but
> it could probably be extended to do so. You can find the SVA
> publications at http://sva.cs.illinois.edu/pubs.
> As an aside, my (admittedly biased) opinion is that SVA is a very good
> platform for doing novel things with operating systems and compilers.
> We've used it to protect Linux and FreeBSD from memory safety errors
> using SAFECode-like techniques and simpler control-flow integrity
> approaches, and we'll have a paper out in March on using it to protect
> applications from compromised operating system kernels. We haven't
> open-sourced the code yet, but if you're up for some low-level coding,
> you can write a new implementation of the instructions.
> Finally, regarding TCG, I'm not sure that TCG will be that much better a
> fit than LLVM IR. TCG doesn't have pointer sizes the way LLVM does, but
> all of your loads and stores will still have a size argument (8, 16, 32,
> 64 bits). It is not clear to me that a TCG program can be converted
> from working with 32-bit pointers to 64-bit pointers automatically.
> Also, I think LLVM provides many more optimizations than TCG and makes
> writing optimizations and code transformations easier.
> Hope some of this helps,
> -- John T.
> > Julien
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