[LLVMdev] Building a stable bitcode format for PNaCl - based on LLVM IR

[Dmitri Rubinstein]

Am 19.06.2013 18:01, schrieb JF Bastien:
>
>      From the provided documentation I understood that in memory data
>     structures of a PNaCl program are incompatible to the host program
>     because ABIs are different (e.g. PNaCl pointers are always 32-bit
>     even when running on x86_64 platform).
>     So PNaCl program can't access any data structures of the host
>     program directly. The only communication way is by using syscalls,
>     but the document does not specify syscalls in detail.
>
>
> We should probably clarify in the final documentation, but the goal of
> PNaCl is to not only be portable and fast but also be safe for the user,
> and the way this is achieved is through NaCl's SFI. Specifically for
> syscalls:
> http://www.chromium.org/nativeclient/reference/anatomy-of-a-sys
> In a way the syscalls offered are defined by the embedding sandbox: NaCl
> through Chrome and sel_ldr have documented interfaces, and the NaCl SDK
> offers POSIX-like interfaces built on top of these.

But this discussion is about stable bitcode format, or do you want to 
restrict the set of syscalls on the LLVM level ?
I am interested for my project in having a stable portable bitcode 
format like the one you propose, but not as a part of a browser and I 
possibly need to have an extended set of syscalls. The documentation 
does not provide an example how the syscall is represented in the LLVM 
bitcode. Is this just a function call ?

Best,

Dmitri