ArmVirtPkg: allow runtime control of serial debug log level via DT by luigix25 · Pull Request #12277 · tianocore/edk2

luigix25 · 2026-03-11T13:24:01Z

Add support for a device-tree property "edk2,debug-level" on PL011 UART nodes. When present, this 32-bit cell overrides the compiled-in DebugPrintErrorLevel for serial port output, allowing the serial verbosity to be tuned at boot time without rebuilding the firmware.

When this property is not present, the original behavior (serial output follows DebugPrintErrorLevel) is preserved.

The memory debug log continues to use the compiled-in level.

Example DT snippet:

pl011@9000000 {
compatible = "arm,pl011";
edk2,debug-level = <0x80000000>;
...
};

Description

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Breaking change?
- Breaking change - Does this PR cause a break in build or boot behavior?
- Examples: Does it add a new library class or move a module to a different repo.
Impacts security?
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Includes tests?
- Tests - Does this PR include any explicit test code?
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How This Was Tested

QEMU changes:

https://lore.kernel.org/qemu-devel/20260311-edk2_arm_serial-v1-1-c25e237116f3@redhat.com/

Integration Instructions

<Describe how these changes should be integrated. Use N/A if nothing is required.>

Add a machine property to pass a debug level to EDK2 firmware via the device tree. The value is set as an "edk2,debug-level" property on all pl011 UART nodes. This is to create a runtime parameter to set the verbosity of the debug log on the serial ports in edk2. Currently, the only way to set the verbosity is a compile-time option. DT is used because the fw_cfg interface is not yet initialized in early boot phases. Corresponding edk2 PR: tianocore/edk2#12277 Suggested-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Luigi Leonardi <leonardi@redhat.com> Message-Id: <20260311-edk2_arm_serial-v1-1-c25e237116f3@redhat.com>

Add a machine property to pass a debug level to EDK2 firmware via the device tree. The value is set as an "edk2,debug-level" property on all pl011 UART nodes. This is to create a runtime parameter to set the verbosity of the debug log on the serial ports in edk2. Currently, the only way to set the verbosity is a compile-time option. DT is used because the fw_cfg interface is not yet initialized in early boot phases. Corresponding edk2 PR: tianocore/edk2#12277 Suggested-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Luigi Leonardi <leonardi@redhat.com> Link: https://lore.kernel.org/qemu-devel/20260311-edk2_arm_serial-v1-1-c25e237116f3@redhat.com

https://lore.kernel.org/qemu-devel/20260311-edk2_arm_serial-v1-1-c25e237116f3@redhat.com --- From: Luigi Leonardi <leonardi@redhat.com> Date: Wed, 11 Mar 2026 14:43:20 +0100 Subject: [PATCH] hw/arm/virt: add serial-debug-level property for EDK2 firmware MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260311-edk2_arm_serial-v1-1-c25e237116f3@redhat.com> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/6tWKk4tykwtVrJSqFYqSi3LLM7MzwNyDHUUlJIzE vPSU3UzU4B8JSMDIzMDY0ND3dSUbKP4xKLceJDGxBzdVBMDIyOzVDNL09QkJaCugqLUtMwKsIn RsbW1APMn66NhAAAA X-Change-ID: 20260311-edk2_arm_serial-e40226e695eb To: qemu-devel@nongnu.org Cc: Peter Maydell <peter.maydell@linaro.org>, Pierrick Bouvier <pierrick.bouvier@linaro.org>, Oliver Steffen <osteffen@redhat.com>, qemu-arm@nongnu.org, Gerd Hoffmann <kraxel@redhat.com>, Luigi Leonardi <leonardi@redhat.com> X-Mailer: b4 0.14.2 Received-SPF: pass client-ip=170.10.129.124; envelope-from=leonardi@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -3 X-Spam_score: -0.4 X-Spam_bar: / X-Spam_report: (-0.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.819, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.903, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, WEIRD_QUOTING=0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development <qemu-devel.nongnu.org> List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>, <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe> List-Archive: <https://lists.nongnu.org/archive/html/qemu-devel> List-Post: <mailto:qemu-devel@nongnu.org> List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help> List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>, <mailto:qemu-devel-request@nongnu.org?subject=subscribe> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Add a machine property to pass a debug level to EDK2 firmware via the device tree. The value is set as an "edk2,debug-level" property on all pl011 UART nodes. This is to create a runtime parameter to set the verbosity of the debug log on the serial ports in edk2. Currently, the only way to set the verbosity is a compile-time option. DT is used because the fw_cfg interface is not yet initialized in early boot phases. Corresponding edk2 PR: tianocore/edk2#12277 Suggested-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Luigi Leonardi <leonardi@redhat.com> --- docs/system/arm/virt.rst | 6 ++++++ hw/arm/virt.c | 38 ++++++++++++++++++++++++++++++++++++++ include/hw/arm/virt.h | 2 ++ 3 files changed, 46 insertions(+) diff --git a/docs/system/arm/virt.rst b/docs/system/arm/virt.rst index fbe3ca9..adba8ff 100644 --- a/docs/system/arm/virt.rst +++ b/docs/system/arm/virt.rst @@ -239,6 +239,12 @@ x-oem-table-id Set string (up to 8 bytes) to override the default value of field OEM Table ID in ACPI table header. +serial-debug-level + Set the EDK2 firmware debug level for serial port output. Valid values are + the debug level bitmasks defined in the EDK2 + `DebugLib.h <https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Library/DebugLib.h>`_ + header (e.g. ``0x00400000`` for ``DEBUG_INFO``). + SMMU configuration """""""""""""""""" diff --git a/hw/arm/virt.c b/hw/arm/virt.c index 7456614..bbea1bb 100644 --- a/hw/arm/virt.c +++ b/hw/arm/virt.c @@ -986,6 +986,11 @@ static void create_uart(const VirtMachineState *vms, int uart, nodename = g_strdup_printf("/pl011@%" PRIx64, base); qemu_fdt_add_subnode(ms->fdt, nodename); + if (vms->serial_debug_level_set) { + qemu_fdt_setprop_cell(ms->fdt, nodename, "edk2,debug-level", + vms->serial_debug_level); + } + /* Note that we can't use setprop_string because of the embedded NUL */ qemu_fdt_setprop(ms->fdt, nodename, "compatible", compat, sizeof(compat)); @@ -2869,6 +2874,31 @@ static void virt_set_dtb_randomness(Object *obj, bool value, Error **errp) vms->dtb_randomness = value; } +static char *virt_get_serial_debug_level(Object *obj, Error **errp) +{ + VirtMachineState *vms = VIRT_MACHINE(obj); + return vms->serial_debug_level_set + ? g_strdup_printf("0x%" PRIx32, vms->serial_debug_level) + : g_strdup(""); +} + +static void +virt_set_serial_debug_level(Object *obj, const char *value, Error **errp) +{ + VirtMachineState *vms = VIRT_MACHINE(obj); + uint64_t val; + int ret; + + ret = qemu_strtou64(value, NULL, 0, &val); + if (ret < 0 || val > UINT32_MAX) { + error_setg(errp, "invalid serial-debug-level value '%s', " + "must be a uint32 value", value); + return; + } + vms->serial_debug_level = (uint32_t)val; + vms->serial_debug_level_set = true; +} + static char *virt_get_oem_id(Object *obj, Error **errp) { VirtMachineState *vms = VIRT_MACHINE(obj); @@ -3643,6 +3673,12 @@ static void virt_machine_class_init(ObjectClass *oc, const void *data) "in ACPI table header." "The string may be up to 8 bytes in size"); + object_class_property_add_str(oc, "serial-debug-level", + virt_get_serial_debug_level, + virt_set_serial_debug_level); + object_class_property_set_description(oc, "serial-debug-level", + "Set the EDK2 firmware debug level bitmask for " + "serial port output"); } static void virt_instance_init(Object *obj) @@ -3692,6 +3728,8 @@ static void virt_instance_init(Object *obj) vms->virtio_transports = NUM_VIRTIO_TRANSPORTS; + vms->serial_debug_level_set = false; + virt_flash_create(vms); vms->oem_id = g_strndup(ACPI_BUILD_APPNAME6, 6); diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h index dba8ac7..1dddfa6 100644 --- a/include/hw/arm/virt.h +++ b/include/hw/arm/virt.h @@ -187,6 +187,8 @@ struct VirtMachineState { MemoryRegion *sysmem; MemoryRegion *secure_sysmem; bool pci_preserve_config; + uint32_t serial_debug_level; + bool serial_debug_level_set; }; #define VIRT_ECAM_ID(high) (high ? VIRT_HIGH_PCIE_ECAM : VIRT_PCIE_ECAM) --- base-commit: ae56950 change-id: 20260311-edk2_arm_serial-e40226e695eb Best regards, -- Luigi Leonardi <leonardi@redhat.com> Signed-off-by: GitHub Actions Bot <bot@github.com>

Add `DebugLevel` and `DebugLevelSet` to the `FDT_SERIAL_PORTS` struct. This will be used by ArmVirt, to get the debug log level for serial ports at runtime using the device tree. Signed-off-by: Luigi Leonardi <leonardi@redhat.com>

Add support for a device-tree property "edk2,debug-level" on PL011 UART nodes. When present, this 32-bit cell overrides the compiled-in DebugPrintErrorLevel for serial port output, allowing the serial verbosity to be tuned at boot time without rebuilding the firmware. When this property is not present, the original behavior (serial output follows DebugPrintErrorLevel) is preserved. The memory debug log continues to use the compiled-in level. Example DT snippet: pl011@9000000 { compatible = "arm,pl011"; edk2,debug-level = <0x80000000>; ... }; Suggested-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Luigi Leonardi <leonardi@redhat.com>

osteffenrh · 2026-03-13T12:51:54Z

ArmVirtPkg/Library/DebugLibFdtPL011Uart/Ram.c

+BOOLEAN        mRuntimeDebugLevelSet;
+UINT32         mRuntimeDebugLevel;


Suggested change

BOOLEAN mRuntimeDebugLevelSet;

UINT32 mRuntimeDebugLevel;

BOOLEAN mDebugLibFdtPL011UartRuntimeDebugLevelSet;

UINT32 mDebugLibFdtPL011UartRuntimeDebugLevel;

To avoid possible name conflict from other compilation objects.

osteffenrh · 2026-03-13T14:23:37Z

Apart from the CI and my comment above: LGTM.

I tested with QEMU in tcg mode.
I dumped the original dtb and modified it manyally:

qemu-system-aarch64 -M virt -machine dumpdtb=file.dtb
dtc -I dtb -O dts -o file.dts file.dtb
# modify dts
dtc -I dts -O dtb -o file2.dtb file.dts

qemu-system-aarch64  \
  -machine virt,dtb=./file2.dtb \
  ...

luigix25 force-pushed the arm_dt_level branch from d766a9f to 33502de Compare March 11, 2026 16:15

luigix25 added 2 commits March 11, 2026 17:24

luigix25 force-pushed the arm_dt_level branch from 33502de to a0ac4a2 Compare March 11, 2026 16:24

osteffenrh reviewed Mar 13, 2026

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ArmVirtPkg: allow runtime control of serial debug log level via DT#12277

ArmVirtPkg: allow runtime control of serial debug log level via DT#12277
luigix25 wants to merge 2 commits intotianocore:masterfrom
luigix25:arm_dt_level

luigix25 commented Mar 11, 2026 •

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luigix25 commented Mar 11, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Description

How This Was Tested

Integration Instructions

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osteffenrh Mar 13, 2026

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osteffenrh commented Mar 13, 2026

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luigix25 commented Mar 11, 2026 •

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