On 2/20/2026 9:39 AM, Andre Przywara wrote:

On Mon, 19 Jan 2026 12:27:29 +0000
Salman Nabi [off-list ref] wrote:

Hey,

for the records: while working on improving the patch and during internal
review, we found some bugs and issues in there. I will mark them below for
the benefit of others. I will send a v2 after -rc1, with those things
fixed and some improvements, and will include Vedashree's patches, so
that we have everything in one series.

quoted

The Arm Live Firmware Activation (LFA) is a specification [1] to describe
activating firmware components without a reboot. Those components
(like TF-A's BL31, EDK-II, TF-RMM, secure paylods) would be updated the
usual way: via fwupd, FF-A or other secure storage methods, or via some
IMPDEF Out-Of-Bound method. The user can then activate this new firmware,
at system runtime, without requiring a reboot.
The specification covers the SMCCC interface to list and query available
components and eventually trigger the activation.

Add a new directory under /sys/firmware to present firmware components
capable of live activation. Each of them is a directory under lfa/,
and is identified via its GUID. The activation will be triggered by echoing
"1" into the "activate" file:
==========================================
/sys/firmware/lfa # ls -l . 6c*
.:
total 0
drwxr-xr-x    2 0 0         0 Jan 19 11:33 47d4086d-4cfe-9846-9b95-2950cbbd5a00
drwxr-xr-x    2 0 0         0 Jan 19 11:33 6c0762a6-12f2-4b56-92cb-ba8f633606d9
drwxr-xr-x    2 0 0         0 Jan 19 11:33 d6d0eea7-fcea-d54b-9782-9934f234b6e4

6c0762a6-12f2-4b56-92cb-ba8f633606d9:
total 0
--w-------    1 0        0             4096 Jan 19 11:33 activate
-r--r--r--    1 0        0             4096 Jan 19 11:33 activation_capable
-r--r--r--    1 0        0             4096 Jan 19 11:33 activation_pending
--w-------    1 0        0             4096 Jan 19 11:33 cancel
-r--r--r--    1 0        0             4096 Jan 19 11:33 cpu_rendezvous
-r--r--r--    1 0        0             4096 Jan 19 11:33 current_version
-rw-r--r--    1 0        0             4096 Jan 19 11:33 force_cpu_rendezvous
-r--r--r--    1 0        0             4096 Jan 19 11:33 may_reset_cpu
-r--r--r--    1 0        0             4096 Jan 19 11:33 name
-r--r--r--    1 0        0             4096 Jan 19 11:33 pending_version
/sys/firmware/lfa/6c0762a6-12f2-4b56-92cb-ba8f633606d9 # grep . *
grep: activate: Permission denied
activation_capable:1
activation_pending:1
grep: cancel: Permission denied
cpu_rendezvous:1
current_version:0.0
force_cpu_rendezvous:1
may_reset_cpu:0
name:TF-RMM
pending_version:0.0
/sys/firmware/lfa/6c0762a6-12f2-4b56-92cb-ba8f633606d9 # echo 1 > activate
[ 2825.797871] Arm LFA: firmware activation succeeded.
/sys/firmware/lfa/6c0762a6-12f2-4b56-92cb-ba8f633606d9 #
==========================================

[1] https://developer.arm.com/documentation/den0147/latest/

Signed-off-by: Salman Nabi <redacted>
---
 drivers/firmware/smccc/Kconfig  |   8 +
 drivers/firmware/smccc/Makefile |   1 +
 drivers/firmware/smccc/lfa_fw.c | 668 ++++++++++++++++++++++++++++++++
 3 files changed, 677 insertions(+)
 create mode 100644 drivers/firmware/smccc/lfa_fw.c

diff --git a/drivers/firmware/smccc/Kconfig b/drivers/firmware/smccc/Kconfig
index 15e7466179a6..ff7ca49486b0 100644
--- a/drivers/firmware/smccc/Kconfig
+++ b/drivers/firmware/smccc/Kconfig

@@ -23,3 +23,11 @@ config ARM_SMCCC_SOC_ID
 	help
 	  Include support for the SoC bus on the ARM SMCCC firmware based
 	  platforms providing some sysfs information about the SoC variant.
+
+config ARM_LFA
+	tristate "Arm Live Firmware activation support"
+	depends on HAVE_ARM_SMCCC_DISCOVERY

As the kernel test robot correctly pointed out, this only works on ARM64.
SMCCC v1.2 is only defined for AArch64, and the LFA spec documents
actually explicitly mentions AArch64-only at the beginning.

Thank you for the update. How to test these patches outside of NVIDIA devices?
Is it possible to test them on the QEMU or FVP? Any instructions on doing
these tests will be helpful w/ the virtual platforms. 

---Trilok Soni