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From: "Thomas Weißschuh" <linux@weissschuh.net>
To: Willy Tarreau <w@1wt.eu>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Nicolas Schier <nicolas@fjasle.eu>, Shuah Khan <shuah@kernel.org>,
	linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-kselftest@vger.kernel.org
Subject: Re: [PATCH RFC 0/3] selftests/nolibc: avoid spurious kernel relinks
Date: Sun, 17 Sep 2023 16:44:22 +0200	[thread overview]
Message-ID: <5200f33b-f4ba-4251-bee0-3ae7257e22d2@t-8ch.de> (raw)
In-Reply-To: <20230917032219.GH9646@1wt.eu>

On 2023-09-17 05:22:19+0200, Willy Tarreau wrote:
> On Sat, Sep 16, 2023 at 09:13:26AM +0200, Thomas Weißschuh wrote:
> > Currently the nolibc testsuite embeds the test executable into a kernel
> > image with CONFIG_INITRAMFS_SOURCE.
> > This forces a full kernel relink everytime the test executable is
> > updated.
> > 
> > This relinking step dominates the test cycle.
> > It is slower than building and running the test in qemu together.
> > 
> > With a bit of Makefile-shuffling the relinking can be avoided.
> 
> That's pretty nice as indeed it still takes a while to relink it into
> the kernel. I agree that for running nolibc-test in qemu we don't need
> a unified image. However I've seldom used it on real hardware and I
> find it significantly more convenient to use as a single image in this
> case. Maybe we should just rename targets so that everything qemu-related
> just uses two distinct images while a "unified-image" (or anything else)
> still assembles the image into the kernel (BTW the help on the "kernel"
> target still mentions initramfs).

Sounds good, "unified-image" is a bit close to "unified kernel image"
(UKI) which is similar but different.

What about kernel-standalone?

> Note that we don't need to modify anything in the build system to create
> an initrd, I usually make them by hand using "cpio -o -H newc", we don't
> need anything else here.

I'd like to keep the build self-contained. But actually the kernel build
will always build a minimal initramfs if CONFIG_BLK_DEV_INITRD is set.
This config is needed for the nolibc testsuite in any case.

The fact that the initrd is always build means that usr/gen_init_cpio
is also always build.
So we can add "kernel" as a prerequisite to "initramfs.cpio" and
everything should work out without any buildsystem modifications.

> Regarding rerun, I'd rather keep it for the sole reason that I've used
> it to check for randomly failing errors (typically the timing-based
> ones). It's convenient to run the same image 100 times if needed. I'm
> not strongly attached to it, but if "make run" is slower, then we can
> keep it. However if you really want to drop it, it also needs to be
> dropped from the help message ;-)

Fine for me, let's keep it :-)

      reply	other threads:[~2023-09-17 14:45 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-16  7:13 [PATCH RFC 0/3] selftests/nolibc: avoid spurious kernel relinks Thomas Weißschuh
2023-09-16  7:13 ` [PATCH RFC 1/3] kbuild: add toplevel target for usr/gen_init_cpio Thomas Weißschuh
2023-09-16 15:54   ` Masahiro Yamada
2023-09-16  7:13 ` [PATCH RFC 2/3] selftests/nolibc: don't embed initramfs into kernel image Thomas Weißschuh
2023-09-16  7:13 ` [PATCH RFC 3/3] selftests/nolibc: drop target "rerun" Thomas Weißschuh
2023-09-17  3:22 ` [PATCH RFC 0/3] selftests/nolibc: avoid spurious kernel relinks Willy Tarreau
2023-09-17 14:44   ` Thomas Weißschuh [this message]

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