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h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=L7mkoktXP5v0/RPVXM+q7CecPRvSeFXAVpTa/6Zi4HnKjplmUZN/H5wnjKazdmLdp H8M4zx8EUPxaLtXjGTqFH4oB6mjnLPWC/BSPgdkl4h2qIjZ/HPjQL5aCE1C0JM/lhq Le4s1EByn67fR4X3Sa7CgHV2tayNiIxZZYNGWS0+oRh+u/liq2Tsmx8K7sVndzLSmb B0Z/FnUjSciukjiyp38oAqsfq7wdzGJRRZK4KfYUMTPZauyEEJt4T0srAwNTH5//SU s/XWZE0wl+KGlzUFup0xv2Cgj76r0cxJJKixyGJzRWoML2Ql4GrYceFXQiAQ8Lx1rb G7k8chNnYAEAA== From: Pratyush Yadav To: Breno Leitao Cc: Alexander Graf , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, usamaarif642@gmail.com, rmikey@meta.com, clm@fb.com, riel@surriel.com, kernel-team@meta.com Subject: Re: [PATCH v3 1/2] kho: history: track previous kernel version In-Reply-To: <20260108-kho-v3-1-b1d6b7a89342@debian.org> (Breno Leitao's message of "Thu, 08 Jan 2026 08:40:58 -0800") References: <20260108-kho-v3-0-b1d6b7a89342@debian.org> <20260108-kho-v3-1-b1d6b7a89342@debian.org> Date: Wed, 14 Jan 2026 19:19:11 +0000 Message-ID: <2vxzy0m0gfyo.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Stat-Signature: rgq1j7z6i79j811cmth38jrm5bq1y679 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: C39DC40002 X-Rspam-User: X-HE-Tag: 1768418356-877557 X-HE-Meta: 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 bHTpyVzn +JQZycI9YENo0OrYvAR44Q3ojOvoe+MIh07lWPeVqOrM0F8aPYmmuhhDRQ5o2Ut6I7vKC3dfuhqNEhWF3WDyPOz1WfaHEfnlaMy5OY6g2bvbZrgB7OR3LOqdUN7mYqabjDfCrCsAGbTWwmYBfW+fv5wFGOaheB7XbRK38etfFeYAq554ZNZARLYNEIDehPmfNo0Yq X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Breno, On Thu, Jan 08 2026, Breno Leitao wrote: > Store and display the kernel version from the previous kexec boot. > > The current kernel's release string is saved to the "previous-release" > property in the KHO FDT before kexec. On the next boot, if this property > exists, the previous kernel version is retrieved and printed during > early boot. > > This helps diagnose bugs that only manifest when kexecing from specific > kernel versions, making it easier to correlate crashes with the kernel > that initiated the kexec. The KHO FDT is ABI. So you should be bumping the version number when you make changes to it. But honestly, adding this "optional" stuff to the core KHO ABI makes me uneasy. I say optional since it is not needed for the main functionality of KHO. Making this a part of the ABI increases the surface area we have. The more things we stuff in the ABI, the more inflexible it gets over time. Any changes to the KHO ABI means all consumers also need a version bump. This includes LUO and all its users for example. So I would really like to avoid adding optional things in core KHO FDT. The easy fix is to add a separate subtree for the optional metadata. You would still need to create an ABI for the data format, but being independent of core KHO, it will make it more flexible and easier to change in the future. You can keep the code in kexec_handover.c. > > Signed-off-by: Breno Leitao [...] -- Regards, Pratyush Yadav