From: Yazen Ghannam <yazen.ghannam@amd.com>
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 <yazen.ghannam@amd.com>
Co-developed-by: "Mario Limonciello (AMD)" <superm1@kernel.org>
Signed-off-by: "Mario Limonciello (AMD)" <superm1@kernel.org>
---
v6:
* rename print AGESA function (Boris)
* check count explicitly
* remove extra comments
* Only print second half of string, look for full !V9 sentinel
v5:
* Return "" in !CONFIG_DMI case (LKP robot, Yazen)
v4:
* New patch (based upon older versions though)
---
arch/x86/kernel/cpu/amd.c | 49 +++++++++++++++++++++++++++++++++++++
drivers/firmware/dmi_scan.c | 3 ++-
include/linux/dmi.h | 18 ++++++++++++++
3 files changed, 69 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 09de584e4c8fa..f4d1b4ee155b3 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 <linux/export.h>
#include <linux/bitops.h>
+#include <linux/dmi.h>
#include <linux/elf.h>
#include <linux/mm.h>
#include <linux/kvm_types.h>
@@ -1380,3 +1381,51 @@ static __init int print_s5_reset_status_mmio(void)
return 0;
}
late_initcall(print_s5_reset_status_mmio);
+
+static void __init dmi_scan_additional(const struct dmi_header *d, void *p)
+{
+ struct dmi_a_info *info = (struct dmi_a_info *)d;
+ void *next, *end;
+
+ if (!IS_ENABLED(CONFIG_DMI))
+ return;
+
+ if (info->header.type != DMI_ENTRY_ADDITIONAL ||
+ info->header.length < DMI_A_INFO_MIN_SIZE ||
+ info->count < 1)
+ return;
+
+ next = (void *)(info + 1);
+ end = (void *)info + info->header.length;
+
+ do {
+ struct dmi_a_info_entry *entry;
+ const char *string_ptr;
+
+ entry = (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 = dmi_string_nosave(&info->header, entry->str_num);
+
+ /* Sample string: AGESA!V9 StrixKrackanPI-FP8 1.1.0.0c */
+ if (!strncmp(string_ptr, "AGESA!V9", 8) && strlen(string_ptr) > 9) {
+ pr_info("AGESA: %s\n", string_ptr + 9);
+ break;
+ }
+
+ next += entry->length;
+ } while (end - next >= DMI_A_INFO_ENT_MIN_SIZE);
+}
+
+static __init int print_dmi_agesa(void)
+{
+ dmi_walk(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;
-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 = ((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)
return dmi_empty_string;
}
+EXPORT_SYMBOL_GPL(dmi_string_nosave);
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 */
};
+#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
struct dmi_dev_onboard {
@@ -120,6 +135,7 @@ extern void dmi_memdev_name(u16 handle, const char **bank, 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);
#else
@@ -153,6 +169,8 @@ static inline u8 dmi_memdev_type(u16 handle) { return 0x0; }
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 ""; }
#endif
--
2.43.0On Sat, 7 Mar 2026 08:10:24 -0600, Mario Limonciello (AMD) wrote:
> From: Yazen Ghannam <yazen.ghannam@amd.com>
>
> 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 <yazen.ghannam@amd.com>
> Co-developed-by: "Mario Limonciello (AMD)" <superm1@kernel.org>
> Signed-off-by: "Mario Limonciello (AMD)" <superm1@kernel.org>
Looks good to me.
Reviewed-by: Jean Delvare <jdelvare@suse.de>
I only have one question:
> (...)
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> (...)
> +static void __init dmi_scan_additional(const struct dmi_header *d, void *p)
> +{
> + struct dmi_a_info *info = (struct dmi_a_info *)d;
> + void *next, *end;
> +
> + if (!IS_ENABLED(CONFIG_DMI))
> + return;
> +
> + if (info->header.type != DMI_ENTRY_ADDITIONAL ||
> + info->header.length < DMI_A_INFO_MIN_SIZE ||
> + info->count < 1)
> + return;
> +
> + next = (void *)(info + 1);
> + end = (void *)info + info->header.length;
> +
> + do {
> + struct dmi_a_info_entry *entry;
> + const char *string_ptr;
> +
> + entry = (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 = dmi_string_nosave(&info->header, entry->str_num);
> +
> + /* Sample string: AGESA!V9 StrixKrackanPI-FP8 1.1.0.0c */
> + if (!strncmp(string_ptr, "AGESA!V9", 8) && strlen(string_ptr) > 9) {
Isn't "V9" going to become "V10" at some point in the future, and then
the AGESA string will no longer be displayed until the code is
adjusted? Or will AMD move the information to a more appropriate place
by then?
Also, I know this was discussed before, but the current print strategy
omits "V9". Is this not something we are going to regret once more
versions are available and we may have to differentiate between them?
> + pr_info("AGESA: %s\n", string_ptr + 9);
> + break;
> + }
> +
> + next += entry->length;
> + } while (end - next >= DMI_A_INFO_ENT_MIN_SIZE);
> +}
--
Jean Delvare
SUSE L3 Support
On Wed, Apr 01, 2026 at 11:17:01AM +0200, Jean Delvare wrote:
> Isn't "V9" going to become "V10" at some point in the future, and then
> the AGESA string will no longer be displayed until the code is
> adjusted? Or will AMD move the information to a more appropriate place
> by then?
>
> Also, I know this was discussed before, but the current print strategy
> omits "V9". Is this not something we are going to regret once more
> versions are available and we may have to differentiate between them?
Right, I think we should not be silly and simply dump the string that starts
with "AGESA" and that's it.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On Wed, Apr 01, 2026 at 12:29:08PM +0200, Borislav Petkov wrote:
> On Wed, Apr 01, 2026 at 11:17:01AM +0200, Jean Delvare wrote:
> > Isn't "V9" going to become "V10" at some point in the future, and then
> > the AGESA string will no longer be displayed until the code is
> > adjusted? Or will AMD move the information to a more appropriate place
> > by then?
> >
> > Also, I know this was discussed before, but the current print strategy
> > omits "V9". Is this not something we are going to regret once more
> > versions are available and we may have to differentiate between them?
>
> Right, I think we should not be silly and simply dump the string that starts
> with "AGESA" and that's it.
IOW, this:
if (!strncmp(string_ptr, "AGESA", 5)) {
pr_info("AGESA: %s\n", string_ptr);
break;
}
Mario, what's that additional "dance" you're doing there? Do we have other
strings which start with "AGESA"?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On 4/1/26 06:45, Borislav Petkov wrote:
> On Wed, Apr 01, 2026 at 12:29:08PM +0200, Borislav Petkov wrote:
>> On Wed, Apr 01, 2026 at 11:17:01AM +0200, Jean Delvare wrote:
>>> Isn't "V9" going to become "V10" at some point in the future, and then
>>> the AGESA string will no longer be displayed until the code is
>>> adjusted? Or will AMD move the information to a more appropriate place
>>> by then?
>>>
>>> Also, I know this was discussed before, but the current print strategy
>>> omits "V9". Is this not something we are going to regret once more
>>> versions are available and we may have to differentiate between them?
>>
>> Right, I think we should not be silly and simply dump the string that starts
>> with "AGESA" and that's it.
>
> IOW, this:
>
> if (!strncmp(string_ptr, "AGESA", 5)) {
> pr_info("AGESA: %s\n", string_ptr);
> break;
> }
>
> Mario, what's that additional "dance" you're doing there? Do we have other
> strings which start with "AGESA"?
>
Right we did talk about this a little on the last iteration too [1].
The string_ptr + 9 will fail if we ever had a V10.
Link:
https://lore.kernel.org/all/20260126154037.GBaXeK9bxgPMdE2lFr@fat_crate.local/
[1]
If you guys would prefer to stick to the simple strncmp() + pr_info()
the whole thing that's fine by me.
Do you want me to send out a new patch series, or will you just adjust
while committing?
On Wed, Apr 01, 2026 at 08:14:22AM -0500, Mario Limonciello (AMD) wrote:
> If you guys would prefer to stick to the simple strncmp() + pr_info() the
> whole thing that's fine by me.
>
> Do you want me to send out a new patch series, or will you just adjust while
> committing?
Nah, I'll fix up everything.
The idea is that it is very simple this way and also future-proof. We can
always change it if it *turns out* that it is needed but anticipating things
is not really necessary I'd say.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
The following commit has been merged into the x86/platform branch of tip:
Commit-ID: bc91133e260c8113c1119073c03b93c12aa41738
Gitweb: https://git.kernel.org/tip/bc91133e260c8113c1119073c03b93c12aa41738
Author: Yazen Ghannam <yazen.ghannam@amd.com>
AuthorDate: Sat, 07 Mar 2026 08:10:24 -06:00
Committer: Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Wed, 01 Apr 2026 20:54:16 +02:00
x86/CPU/AMD: Print AGESA string from DMI additional information entry
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.
[ bp: Match only "AGESA". ]
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Co-developed-by: "Mario Limonciello (AMD)" <superm1@kernel.org>
Signed-off-by: "Mario Limonciello (AMD)" <superm1@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Link: https://patch.msgid.link/20260307141024.819807-6-superm1@kernel.org
---
arch/x86/kernel/cpu/amd.c | 49 ++++++++++++++++++++++++++++++++++++-
drivers/firmware/dmi_scan.c | 3 +-
include/linux/dmi.h | 18 +++++++++++++-
3 files changed, 69 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 09de584..33b740c 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 <linux/export.h>
#include <linux/bitops.h>
+#include <linux/dmi.h>
#include <linux/elf.h>
#include <linux/mm.h>
#include <linux/kvm_types.h>
@@ -1380,3 +1381,51 @@ static __init int print_s5_reset_status_mmio(void)
return 0;
}
late_initcall(print_s5_reset_status_mmio);
+
+static void __init dmi_scan_additional(const struct dmi_header *d, void *p)
+{
+ struct dmi_a_info *info = (struct dmi_a_info *)d;
+ void *next, *end;
+
+ if (!IS_ENABLED(CONFIG_DMI))
+ return;
+
+ if (info->header.type != DMI_ENTRY_ADDITIONAL ||
+ info->header.length < DMI_A_INFO_MIN_SIZE ||
+ info->count < 1)
+ return;
+
+ next = (void *)(info + 1);
+ end = (void *)info + info->header.length;
+
+ do {
+ struct dmi_a_info_entry *entry;
+ const char *string_ptr;
+
+ entry = (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 = dmi_string_nosave(&info->header, entry->str_num);
+
+ /* Sample string: AGESA!V9 StrixKrackanPI-FP8 1.1.0.0c */
+ if (!strncmp(string_ptr, "AGESA", 5)) {
+ pr_info("AGESA: %s\n", string_ptr);
+ break;
+ }
+
+ next += entry->length;
+ } while (end - next >= DMI_A_INFO_ENT_MIN_SIZE);
+}
+
+static __init int print_dmi_agesa(void)
+{
+ dmi_walk(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 ed6235a..a3f7dab 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;
-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 = ((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)
return dmi_empty_string;
}
+EXPORT_SYMBOL_GPL(dmi_string_nosave);
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 2eedf44..c8700e6 100644
--- a/include/linux/dmi.h
+++ b/include/linux/dmi.h
@@ -91,6 +91,21 @@ struct dmi_device {
void *device_data; /* Type specific data */
};
+#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
struct dmi_dev_onboard {
@@ -120,6 +135,7 @@ extern void dmi_memdev_name(u16 handle, const char **bank, 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);
#else
@@ -153,6 +169,8 @@ static inline u8 dmi_memdev_type(u16 handle) { return 0x0; }
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 ""; }
#endif
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