linux-kernel - Potential config regression after 89cde455 ("kexec: consolidate kexec and crash options into kernel/Kconfig.kexec")

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Date:   Mon, 20 Nov 2023 22:52:52 +0000
From:   Ignat Korchagin <ignat@...udflare.com>
To:     eric.devolder@...cle.com
Cc:     linux@...linux.org.uk, catalin.marinas@....com, will@...nel.org,
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Subject: Potential config regression after 89cde455 ("kexec: consolidate kexec
 and crash options into kernel/Kconfig.kexec")

Good day!

We have recently started to evaluate Linux 6.6 and noticed that we
cannot disable CONFIG_KEXEC anymore, but keep CONFIG_CRASH_DUMP
enabled. It seems to be related to commit 89cde455 ("kexec:
consolidate kexec and crash options into kernel/Kconfig.kexec"), where
a CONFIG_KEXEC dependency was added to CONFIG_CRASH_DUMP.

In our current kernel (Linux 6.1) we only enable CONFIG_KEXEC_FILE
with enforced signature check to support the kernel crash dumping
functionality and would like to keep CONFIG_KEXEC disabled for
security reasons [1].

I was reading the long commit message, but the reason for adding
CONFIG_KEXEC as a dependency for CONFIG_CRASH_DUMP evaded me. And I
believe from the implementation perspective CONFIG_KEXEC_FILE should
suffice here (as we successfully used it for crashdumps on Linux 6.1).

Is there a reason for adding this dependency or is it just an
oversight? Would some solution of requiring either CONFIG_KEXEC or
CONFIG_KEXEC_FILE work here?

Ignat

[1]: https://mjg59.dreamwidth.org/28746.html