Re: [PATCH V2 01/15] selftests/x86/sgx: Fix a benign linker warning

[Reinette Chatre]

Hi Dave,

On 10/28/2021 5:26 PM, Dave Hansen wrote:
> On 10/28/21 1:37 PM, Reinette Chatre wrote:
> > From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> >
> > Pass a build id of "none" to the linker to suppress a warning about the
> > build id being ignored:
> >
> >    /usr/bin/ld: warning: .note.gnu.build-id section discarded, --build-id
> >    ignored.
>
> Do we have a good grasp on why this is producing a warning in the first
> place?  This seems like something that could get merged quickly with one
> more sentence in the changelog.

How about a new changelog as below:

The enclave binary (test_encl.elf) is built with only three sections 
(tcs, text, and data) as controlled by its custom linker script.

If gcc is built with "--enable-linker-build-id" (this appears to be a 
common configuration even if it is by default off) then gcc will pass 
"--build-id" to the linker that will prompt it (the linker) to to write 
unique bits identifying the linked file to a ".note.gnu.build-id" section.

The section ".note.gnu.build-id" does not exist in the test enclave 
resulting in the following warning emitted by the linker:

/usr/bin/ld: warning: .note.gnu.build-id section discarded, --build-id 
ignored

The test enclave does not use the build id within the binary so fix the 
warning by passing a build id of "none" to the linker that will disable 
the setting from any earlier "--build-id" options and thus disable the 
attempt to write the build id to a ".note.gnu.build-id" section that 
does not exist.

Reinette