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Re: Kconfig vs tool chain capabilities
On 25.08.20 09:48, Jan Beulich wrote:
On 25.08.2020 09:43, Jürgen Groß wrote:
On 25.08.20 09:34, Jan Beulich wrote:
On 25.08.2020 09:12, Jürgen Groß wrote:
I think both problems can be solved at the same time via the following
approach:
- collect the data which is reflected in today's CONFIG_ variables in a
single script and store it in a file, e.g in a format like:
CC_IS_GCC y
GCC_VERSION 70500
CLANG_VERSION 0
CC_HAS_VISIBILITY_ATTRIBUTE y
- check the tool data at each build to match the contents of that file
and either fail the build or update the file and rerun kconfig if they
don't match (I think failing the build and requiring to run a
"make config" would be the better approach)
- fill the CONFIG_ variable contents from that file in kconfig instead
of issuing the single shell commands
While I agree this is a possible model to use (but still not the
one we've inherited from Linux), I fail to see how this addresses
my "developers should be aware of what they do (not) build and
test" concern: There'd still be dependencies of Kconfig options
on the tool chain capabilities, and their prompts therefore would
still be invisible without the tool chain having the needed
capabilities. IOW I only see this to address 2), but not 1).
Sorry, I fail to see a problem here.
What sense does it make to be able to configure an option which the
tools don't support?
Take CET as an example (chosen because that's the one which
already uses the Kconfig approach, despite my disagreement): It's
quite relevant to know whether you're testing Xen with it enabled,
or with it disabled (and hence you potentially missing changes you
need to make to relevant code portions).
Correct me if I'm wrong, but assuming my suggested changes being made,
wouldn't a .config file setup once with CET enabled (and I assume you'd
try to enable CET on purpose when trying to test CET and you'd realize
not being able to do so in case your tools don't support CET) ensure
you'd never been hit by surprise when some tool updates would remove
CET support?
Why aren't you concerned that you can't configure
ARM-specific options in an x86 build then?
I can't see how this is related.
You are asking for a way to select options not supported by the tools.
This is very similar to asking for the possibility to select options
not supported by the architecture.
Juergen
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