From aeb709c767aeca996e6011133e4f7bdb2a4af652 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Wed, 30 Sep 2026 09:59:20 +0000 Subject: selftests/bpf: Add a test for objects stuck in free_by_rcu_ttrace Delete all elements of BPF_F_NO_PREALLOC hash map in one batch. The first free_bulk() starts RCU tasks trace GP and the rest of the elements are freed while it's in flight. Wait for call_rcu_ttrace_in_progress to clear in bpf_mem_cache of every cpu and check that free_by_rcu_ttrace and waiting_for_gp_ttrace lists are empty. Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20260930095920.601738-4-alexei.starovoitov@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- Documentation/driver-api/ipmb.rst | 109 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 109 insertions(+) create mode 100644 Documentation/driver-api/ipmb.rst (limited to 'Documentation/driver-api/ipmb.rst') diff --git a/Documentation/driver-api/ipmb.rst b/Documentation/driver-api/ipmb.rst new file mode 100644 index 000000000..209c49e05 --- /dev/null +++ b/Documentation/driver-api/ipmb.rst @@ -0,0 +1,109 @@ +============================== +IPMB Driver for a Satellite MC +============================== + +The Intelligent Platform Management Bus or IPMB, is an +I2C bus that provides a standardized interconnection between +different boards within a chassis. This interconnection is +between the baseboard management (BMC) and chassis electronics. +IPMB is also associated with the messaging protocol through the +IPMB bus. + +The devices using the IPMB are usually management +controllers that perform management functions such as servicing +the front panel interface, monitoring the baseboard, +hot-swapping disk drivers in the system chassis, etc... + +When an IPMB is implemented in the system, the BMC serves as +a controller to give system software access to the IPMB. The BMC +sends IPMI requests to a device (usually a Satellite Management +Controller or Satellite MC) via IPMB and the device +sends a response back to the BMC. + +For more information on IPMB and the format of an IPMB message, +refer to the IPMB and IPMI specifications. + +IPMB driver for Satellite MC +---------------------------- + +ipmb-dev-int - This is the driver needed on a Satellite MC to +receive IPMB messages from a BMC and send a response back. +This driver works with the I2C driver and a userspace +program such as OpenIPMI: + +1) It is an I2C slave backend driver. So, it defines a callback + function to set the Satellite MC as an I2C slave. + This callback function handles the received IPMI requests. + +2) It defines the read and write functions to enable a user + space program (such as OpenIPMI) to communicate with the kernel. + + +Load the IPMB driver +-------------------- + +The driver needs to be loaded at boot time or manually first. +First, make sure you have the following in your config file: +CONFIG_IPMB_DEVICE_INTERFACE=y + +1) If you want the driver to be loaded at boot time: + +a) Add this entry to your ACPI table, under the appropriate SMBus:: + + Device (SMB0) // Example SMBus host controller + { + Name (_HID, "") // Vendor-Specific HID + Name (_UID, 0) // Unique ID of particular host controller + : + : + Device (IPMB) + { + Name (_HID, "IPMB0001") // IPMB device interface + Name (_UID, 0) // Unique device identifier + } + } + +b) Example for device tree:: + + &i2c2 { + status = "okay"; + + ipmb@10 { + compatible = "ipmb-dev"; + reg = <0x10>; + i2c-protocol; + }; + }; + +If xmit of data to be done using raw i2c block vs smbus +then "i2c-protocol" needs to be defined as above. + +2) Manually from Linux:: + + modprobe ipmb-dev-int + + +Instantiate the device +---------------------- + +After loading the driver, you can instantiate the device as +described in 'Documentation/i2c/instantiating-devices.rst'. +If you have multiple BMCs, each connected to your Satellite MC via +a different I2C bus, you can instantiate a device for each of +those BMCs. + +The name of the instantiated device contains the I2C bus number +associated with it as follows:: + + BMC1 ------ IPMB/I2C bus 1 ---------| /dev/ipmb-1 + Satellite MC + BMC1 ------ IPMB/I2C bus 2 ---------| /dev/ipmb-2 + +For instance, you can instantiate the ipmb-dev-int device from +user space at the 7 bit address 0x10 on bus 2:: + + # echo ipmb-dev 0x1010 > /sys/bus/i2c/devices/i2c-2/new_device + +This will create the device file /dev/ipmb-2, which can be accessed +by the user space program. The device needs to be instantiated +before running the user space program. -- cgit v1.3.1