[lldb-dev] When should ArchSpecs match?

via lldb-dev lldb-dev at lists.llvm.org
Fri Dec 7 08:06:31 PST 2018

We use 2 triples for Hexagon:

hexagon-unknown-elf (which becomes hexagon-unknown-unknown-elf internally), and hexagon-unknown-linux.


We follow the Linux standard and add in magic to the elf to identify it as a Linux binary. But in the hexagon-unknown-elf case we have no way to distinguish between standalone (no OS, running on our simulator) or QuRT (proprietary OS, could be running on hardware or simulator). In fact, the same shared library that has no OS calls (just standard library calls that go into the appropriate .so) could run under either one.


I think requiring a value for every OS would be a non-starter for us.



Ted Woodward

Qualcomm Innovation Center, Inc.

Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project


From: lldb-dev <lldb-dev-bounces at lists.llvm.org> On Behalf Of Zachary Turner via lldb-dev
Sent: Friday, December 7, 2018 4:38 AM
To: Pavel Labath <pavel at labath.sk>
Cc: LLDB <lldb-dev at lists.llvm.org>
Subject: Re: [lldb-dev] When should ArchSpecs match?


We can already say that with OSType::Unknown. That’s different than “i know that no OS exists”

On Fri, Dec 7, 2018 at 12:00 AM Pavel Labath <pavel at labath.sk <mailto:pavel at labath.sk> > wrote:

On 07/12/2018 01:22, Jason Molenda via lldb-dev wrote:
> Oh sorry I missed that.  Yes, I think a value added to the OSType for NoOS or something would work.  We need to standardize on a textual representation for this in a triple string as well, like 'none'.  Then with arm64-- and arm64-*-* as UnknownVendor + UnknownOS we can have these marked as "compatible" with any other value in the case Adrian is looking at.

Sounds good to me.

As another data point, it is usually impossible to tell from looking at 
an ELF file which os it is intended to run on. You can tell the 
architecture because it's right in the elf header, but that's about it. 
Some OSs get around this by adding a special section like 
.this.is.an.android.binary, but not all of them. So in general, we need 
to be able to say "I have no idea which OS is this binary intended for".


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