Re: [PATCH v2 03/14] x86/shstk: Introduce Supervisor Shadow Stack support

[Jan Beulich <jbeulich@xxxxxxxx>]

On 02.06.2020 14:26, Anthony PERARD wrote:
> On Tue, Jun 02, 2020 at 02:06:11PM +0200, Jan Beulich wrote:
>> I don't recall; perhaps I was in another parallel session? If it's
>> the one with notes at
>> https://lists.xenproject.org/archives/html/xen-devel/2019-07/msg00786.html
>> then a remark close to the top suggests I was there, but there's no
>> sign of this aspect having got discussed. There is, among the issues
>> listed, "Xen build re-evaluates compiler support for every translation
>> unit", but that's only remotely related.
> 
> What is a "translation unit"? What would that have to do with Kconfig?

A translation unit is the collective input from all source and
header files seen by the compiler during the processing of one
top level input file's worth of compilation. The connection to
Kconfig here is that by switching to it, the compiler flags
don't get re-constructed once per CU. Of course doing it via
Kconfig is not the only possible solution to the problem (as
can be seen from the patch that I had intermediately submitted
to get at least the HAVE_AS_* out of that set), but for us the
change in behavior is one intended (side-)effect of the switch
to newer Kconfig.

Jan