From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9790932E6B1 for ; Mon, 26 Jan 2026 10:52:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769424734; cv=none; b=FhvOtlHpIoOJK8mWpIDfmiMmoHCY2Jo/LEncRoV0SL76gdQYvMWrLgRftgcZJ2SXEo/DVQPYc8MW8/mfd8SxaXQqMntAZgeJPy+8j/VpxI5bnEgNEIsEpduGiYmCmSrUGPS8rXHniI9J9piN74/0zOxuBqVesxRIIgIeTmnskDI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769424734; c=relaxed/simple; bh=rsJVzIrsc8WbxPF3MQyB2GjdVI3ENEY9cJqGQunzBJ4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DOPXVJXLCBmirwJ7ZV2S8Srwf4jklVs9jDc32YlD/Q8UImdV6Ogs5b4RSUtSPOumxxqnR9tpO0YbaMM+jNIrLZByi4bARXLrDWn2MPolI2aybyXCrzfbvGtG/ZjMqvNuWokeG1jT/iJpTZWS79oQcK95cmV/DUX30mqzO5gksao= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org; spf=none smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=FoeaBPY0; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="FoeaBPY0" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=JOwl1LOtoKU5/PoRXFyQSq1478e5eRvje0/beAymu74=; b=FoeaBPY0sUru0rq2ib8j3XoHP0 jLisWlOIFORxUfmSwSfaBPksTO0/3iVT4cjfhskdL07owgh01DLsc9Vxkf8bEnYpffwyo7XjcMyfV LoXFCdyb2d/U03jgFLE6O/Pdnffd91i9BOd3NM0vnV7E1EoHsFeMFyqUDX5kAx5xC6ncJWcd6Cq7b wY38oXTrfyD0C1tJujuVRBPeOgbCDNdeONtJ8frbYHDDRQLthI38YiqGTcN4K457qBhgb1Cv8qy4K D9R84n7FKPlZZH813+eIw70MV1hqEOcLPZ92rcv4OZF2x/FE5lWDAQpQ3Dp/vi+7Y4hew5+/pCG5r M2foYQNQ==; Received: from authenticated user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94.2) (envelope-from ) id 1vkKCR-00G7ie-Sd; Mon, 26 Jan 2026 10:52:04 +0000 Date: Mon, 26 Jan 2026 02:51:58 -0800 From: Breno Leitao To: Mike Rapoport Cc: Alexander Graf , 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, SeongJae Park Subject: Re: [PATCH v4] kho: kexec-metadata: track previous kernel chain Message-ID: References: <20260121-kho-v4-1-5c8fe77b6804@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Debian-User: leitao On Sun, Jan 25, 2026 at 01:32:27PM +0200, Mike Rapoport wrote: > On Thu, Jan 22, 2026 at 04:04:55AM -0800, Breno Leitao wrote: > > Ack! I am planning something as: > > > > commit 90e098ca0d611b44594f08e50ba1cff3c932dd2b > > Author: Breno Leitao > > Date: Thu Jan 22 03:47:23 2026 -0800 > > > > kho: document kexec-metadata tracking feature ... > I'd move this section before "debugfs Interfaces", other than that LGTM. Ack! > > > Can't we move it into the existing if (fdt) below? > > > > Unfortunately, that won't work due to a data dependency between the two > > functions. > > > > kho_process_kexec_metadata() reads from the FDT subtree and populates kho_in: > > > > Basically: > > > > kho_in.kexec_count = metadata->kexec_count; > > > > While kho_populate_kexec_metadata() increments metadata->kexec_count: > > > > /* kho_in.kexec_count is set to 0 on cold boot */ > > metadata->kexec_count = kho_in.kexec_count + 1; > > > > If kho_process_kexec_metadata() is moved after kho_populate_kexec_metadata(), > > the count would always increment from 0 to 1, ignoring whatever was passed in > > the FDT. > > > > Restructuring to call kho_in_debugfs_init() earlier also doesn't work: > > > > > > if (fdt) { > > kho_in_debugfs_init(&kho_in.dbg, fdt); > > kho_process_kexec_metadata(); > > return 0; > > } > > > > /* Populate kexec metadata for the possible next kexec */ > > err = kho_populate_kexec_metadata(); > > if (err) > > pr_warn("failed to initialize kexec-metadata subtree: %d\n", > > err); > > > > This would return early without populating the kexec metadata for the next > > kexec, breaking the chain on KHO boots. > > How about we rename kho_process_kexec_metadata() to > kho_retreive_kexec_metadata() and add kho_process_kexec_metadata() that > will first call _retrieve and then _populate? Something like > > static int __init kho_process_kexec_metadata(const void *fdt) > { > int err; > > if (fdt) > kho_retrieve_kexec_metadata(); > > /* Populate kexec metadata for the possible next kexec */ > err = kho_populate_kexec_metadata(); > if (err) > pr_warn("failed to initialize kexec-metadata subtree: %d\n", > err); > > return err; > } That would work, I will probably rename it to kho_kexec_metadata_init() or kho_kexec_metadata_setup() to follow the same pattern already there. Thanks for the review, I will send an updated version soon, --breno