From nobody Sat Feb 7 07:44:07 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 949F02EDD45 for ; Fri, 23 Jan 2026 21:31:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769203868; cv=none; b=cZw9jXg2Yt58Eq8FYAlzhzauFRG6YG9qB8yAfmo2yXt8p5O48tBM1HNMLx6rnUiiva8E5piwlIyVJTnKDSbxjysWHejUdGqyCVZbt3dYsX6vF/vdgkjuBXtWGqu47wfLqmgy5Y3/MY6xkP2YByZ/cATUCr13P7OAOvj1zdyTf10= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769203868; c=relaxed/simple; bh=9GhVmE30ogo5YRy74mlJzUk+c2FDiswFFCSId7Ma0W8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Fq2h52DWV6zeT2JWxXUIVVN07iCu6lag1yrAtxKKV2N8FUpuBBBGG4vSf+kNvYeVh2FGA7Cs9jfm3jWnbhoYUxpbkRwL32G8ahrwkCH+AEiwr62PtZi1C4oRaQvCw32sWR+A+mzlPiiep5TuMNoCyPjqWRCDGH+1VeuLA2jnhP0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BpyE77+s; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BpyE77+s" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3A14C4CEF1; Fri, 23 Jan 2026 21:31:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769203868; bh=9GhVmE30ogo5YRy74mlJzUk+c2FDiswFFCSId7Ma0W8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BpyE77+s2VBSQQ6NNvHlGtw60ctkQuxLYUKZPHP/E/TrsUkWXnjCuD1Id3RCfYHL0 oPtAIWaeam3eGArsqtPKd/ZXyGQciVxRvxQ/rRMUFweLU41XOfJxZoFE2z1g/vxCps Eoa8HKO1StHN4wVQT1RJNNXH9UEIi0pbryxQiLSnh6RMxqypC2W9CvB02ylbG9rfN4 bQZIYyHAgf6D6wQ0vzCxQaywaHMsTS5TsH0fPbqxz7HkrXizRyG+OJb3u/NXe4jTWU QJMRuudCYCs5e4wZschdCfAST/c1bnVNDljacGOALGtWvuEhIKGS2jkPSOGvcT2t8R ha4rLTkzoZP2g== From: "Mario Limonciello (AMD)" To: Yazen Ghannam , Jean Delvare Cc: linux-kernel@vger.kernel.org, Borislav Petkov , "Mario Limonciello (AMD)" Subject: [PATCH v5 5/5] x86/CPU/AMD: Print AGESA string from DMI additional information entry Date: Fri, 23 Jan 2026 15:30:56 -0600 Message-ID: <20260123213056.861317-6-superm1@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260123213056.861317-1-superm1@kernel.org> References: <20260123213056.861317-1-superm1@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Yazen Ghannam Type 40 entries (Additional Information) are summarized in section 7.41 as part of the SMBIOS specification. Generally, these entries aren't interesting to save. However on some AMD Zen systems, the AGESA version is stored here. This is useful to save to the kernel message logs for debugging. It can be used to cross-reference issues. Implement an iterator for the Additional Information entries. Use this to find and print the AGESA string. Do so in AMD code, since the use case is AMD-specific. Signed-off-by: Yazen Ghannam Co-developed-by: "Mario Limonciello (AMD)" Signed-off-by: "Mario Limonciello (AMD)" --- v5: * Return "" in !CONFIG_DMI case (LKP robot, Yazen) v4: * New patch (based upon older versions though) --- arch/x86/kernel/cpu/amd.c | 53 +++++++++++++++++++++++++++++++++++++ drivers/firmware/dmi_scan.c | 3 ++- include/linux/dmi.h | 18 +++++++++++++ 3 files changed, 73 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index bc94ff1e250ad..aa04a27aeb107 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0-only #include #include +#include #include #include #include @@ -1404,3 +1405,55 @@ static __init int print_s5_reset_status_mmio(void) return 0; } late_initcall(print_s5_reset_status_mmio); + +static void __init amd_dmi_scan_additional(const struct dmi_header *d, voi= d *p) +{ + struct dmi_a_info *info =3D (struct dmi_a_info *)d; + void *next, *end; + + /* + * DMI Additional Info table has a 'count' field. But it's not very + * helpful since the entries are variable length. So don't use it. + */ + if (info->header.type !=3D DMI_ENTRY_ADDITIONAL || + info->header.length < DMI_A_INFO_MIN_SIZE) + return; + + /* + * Get the first entry. + * The minimum table size guarantees at least one entry is present. + */ + next =3D (void *)(info + 1); + end =3D (void *)info + info->header.length; + + do { + struct dmi_a_info_entry *entry; + const char *string_ptr; + + entry =3D (struct dmi_a_info_entry *)next; + + /* + * Not much can be done to validate data. At least the entry + * length shouldn't be 0. + */ + if (!entry->length) + return; + + string_ptr =3D dmi_string_nosave(&info->header, entry->str_num); + + /* Only one AGESA string is expected. */ + if (!strncmp(string_ptr, "AGESA", 5)) { + pr_info("%s\n", string_ptr); + break; + } + + next +=3D entry->length; + } while (end - next >=3D DMI_A_INFO_ENT_MIN_SIZE); +} + +static __init int print_dmi_agesa(void) +{ + dmi_walk(amd_dmi_scan_additional, NULL); + return 0; +} +late_initcall(print_dmi_agesa); diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c index ed6235ac576b6..a3f7dabd49554 100644 --- a/drivers/firmware/dmi_scan.c +++ b/drivers/firmware/dmi_scan.c @@ -47,7 +47,7 @@ static struct dmi_memdev_info { static int dmi_memdev_nr; static int dmi_memdev_populated_nr __initdata; =20 -static const char * __init dmi_string_nosave(const struct dmi_header *dm, = u8 s) +const char *dmi_string_nosave(const struct dmi_header *dm, u8 s) { const u8 *bp =3D ((u8 *) dm) + dm->length; const u8 *nsp; @@ -66,6 +66,7 @@ static const char * __init dmi_string_nosave(const struct= dmi_header *dm, u8 s) =20 return dmi_empty_string; } +EXPORT_SYMBOL_GPL(dmi_string_nosave); =20 static const char * __init dmi_string(const struct dmi_header *dm, u8 s) { diff --git a/include/linux/dmi.h b/include/linux/dmi.h index 2eedf44e68012..c8700e6a694d1 100644 --- a/include/linux/dmi.h +++ b/include/linux/dmi.h @@ -91,6 +91,21 @@ struct dmi_device { void *device_data; /* Type specific data */ }; =20 +#define DMI_A_INFO_ENT_MIN_SIZE 0x6 +struct dmi_a_info_entry { + u8 length; + u16 handle; + u8 offset; + u8 str_num; + u8 value[]; +} __packed; + +#define DMI_A_INFO_MIN_SIZE 0xB +struct dmi_a_info { + struct dmi_header header; + u8 count; +} __packed; + #ifdef CONFIG_DMI =20 struct dmi_dev_onboard { @@ -120,6 +135,7 @@ extern void dmi_memdev_name(u16 handle, const char **ba= nk, const char **device); extern u64 dmi_memdev_size(u16 handle); extern u8 dmi_memdev_type(u16 handle); extern u16 dmi_memdev_handle(int slot); +const char *dmi_string_nosave(const struct dmi_header *dm, u8 s); =20 #else =20 @@ -153,6 +169,8 @@ static inline u8 dmi_memdev_type(u16 handle) { return 0= x0; } static inline u16 dmi_memdev_handle(int slot) { return 0xffff; } static inline const struct dmi_system_id * dmi_first_match(const struct dmi_system_id *list) { return NULL; } +static inline const char * + dmi_string_nosave(const struct dmi_header *dm, u8 s) { return ""; } =20 #endif =20 --=20 2.43.0