Re: [Buildroot] [PATCH 1/1] linux: fix LINUX_VERSION_PROBED content

From: Thomas Petazzoni via buildroot <buildroot@buildroot.org>
To: Giulio Benetti <giulio.benetti@benettiengineering.com>
Cc: buildroot@buildroot.org
Subject: Re: [Buildroot] [PATCH 1/1] linux: fix LINUX_VERSION_PROBED content
Date: Tue, 7 Feb 2023 15:16:46 +0100	[thread overview]
Message-ID: <20230207151646.09c9df79@windsurf> (raw)
In-Reply-To: <20230104020558.1436469-2-giulio.benetti@benettiengineering.com>

Hello Giulio,

On Wed,  4 Jan 2023 03:05:58 +0100
Giulio Benetti <giulio.benetti@benettiengineering.com> wrote:

> Actually LINUX_VERSION_PROBED is set with the string sorrounded by the
> backquotes including them. So when we evaluate $(LINUX_VERSION_PROBED) we
> end up having the command itself and instead we only need the Linux version
> probed in the style x.y.z.
> 
> Verifying it turns out that:
> 1) --no-print-directory and -s make flags must be passed before -C flag,
> The error was not visible because errors were suppressed with
> '2>/dev/null'  
> 2) backquotes don't evaluate the expression they sorround but become part
> of the string they sorround and get assigned to the variable
> 
> To fix this let's move --no-print-directory right after $(MAKE) and
> use $(shell ) instead of backquotes.
> 
> Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>

What is this fixing exactly? Do you have a specific problem that this
fixes? Or is this just fixing the fact that LINUX_VERSION_PROBED
contains `a very long command` instead of the result of the command
itself?

Indeed, switching back to $(shell ...) like you're proposing would
result in basically backporting:

commit 28f57bb863ba48df054cec0057c844bf23d5969f
Author: Arnout Vandecappelle <arnout@mind.be>
Date:   Sun Jul 12 16:35:27 2015 +0200

    linux: use backtick instead of $(shell ...) make function

    Verified that LINUX_VERSION_PROBED is only used in "-quoted commands
    (actually, usually it's not quoted).

    Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
    Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

which is not desirable, especially if you don't have a good
justification of why the current situation doesn't work.

So for now, I'll mark as Rejected, but if you have a good
justification, you can resend with a better commit log with this
justification.

Best regards,

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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