From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- Documentation/userspace-api/dcdbas.rst | 99 ++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 Documentation/userspace-api/dcdbas.rst (limited to 'Documentation/userspace-api/dcdbas.rst') diff --git a/Documentation/userspace-api/dcdbas.rst b/Documentation/userspace-api/dcdbas.rst new file mode 100644 index 000000000..309cc57a7 --- /dev/null +++ b/Documentation/userspace-api/dcdbas.rst @@ -0,0 +1,99 @@ +=================================== +Dell Systems Management Base Driver +=================================== + +Overview +======== + +The Dell Systems Management Base Driver provides a sysfs interface for +systems management software such as Dell OpenManage to perform system +management interrupts and host control actions (system power cycle or +power off after OS shutdown) on certain Dell systems. + +Dell OpenManage requires this driver on the following Dell PowerEdge systems: +300, 1300, 1400, 400SC, 500SC, 1500SC, 1550, 600SC, 1600SC, 650, 1655MC, +700, and 750. Other Dell software such as the open source libsmbios project +is expected to make use of this driver, and it may include the use of this +driver on other Dell systems. + +The Dell libsmbios project aims towards providing access to as much BIOS +information as possible. See http://linux.dell.com/libsmbios/main/ for +more information about the libsmbios project. + + +System Management Interrupt +=========================== + +On some Dell systems, systems management software must access certain +management information via a system management interrupt (SMI). The SMI data +buffer must reside in 32-bit address space, and the physical address of the +buffer is required for the SMI. The driver maintains the memory required for +the SMI and provides a way for the application to generate the SMI. +The driver creates the following sysfs entries for systems management +software to perform these system management interrupts:: + + /sys/devices/platform/dcdbas/smi_data + /sys/devices/platform/dcdbas/smi_data_buf_phys_addr + /sys/devices/platform/dcdbas/smi_data_buf_size + /sys/devices/platform/dcdbas/smi_request + +Systems management software must perform the following steps to execute +a SMI using this driver: + +1) Lock smi_data. +2) Write system management command to smi_data. +3) Write "1" to smi_request to generate a calling interface SMI or + "2" to generate a raw SMI. +4) Read system management command response from smi_data. +5) Unlock smi_data. + + +Host Control Action +=================== + +Dell OpenManage supports a host control feature that allows the administrator +to perform a power cycle or power off of the system after the OS has finished +shutting down. On some Dell systems, this host control feature requires that +a driver perform a SMI after the OS has finished shutting down. + +The driver creates the following sysfs entries for systems management software +to schedule the driver to perform a power cycle or power off host control +action after the system has finished shutting down: + +/sys/devices/platform/dcdbas/host_control_action +/sys/devices/platform/dcdbas/host_control_smi_type +/sys/devices/platform/dcdbas/host_control_on_shutdown + +Dell OpenManage performs the following steps to execute a power cycle or +power off host control action using this driver: + +1) Write host control action to be performed to host_control_action. +2) Write type of SMI that driver needs to perform to host_control_smi_type. +3) Write "1" to host_control_on_shutdown to enable host control action. +4) Initiate OS shutdown. + (Driver will perform host control SMI when it is notified that the OS + has finished shutting down.) + + +Host Control SMI Type +===================== + +The following table shows the value to write to host_control_smi_type to +perform a power cycle or power off host control action: + +=================== ===================== +PowerEdge System Host Control SMI Type +=================== ===================== + 300 HC_SMITYPE_TYPE1 + 1300 HC_SMITYPE_TYPE1 + 1400 HC_SMITYPE_TYPE2 + 500SC HC_SMITYPE_TYPE2 + 1500SC HC_SMITYPE_TYPE2 + 1550 HC_SMITYPE_TYPE2 + 600SC HC_SMITYPE_TYPE2 + 1600SC HC_SMITYPE_TYPE2 + 650 HC_SMITYPE_TYPE2 + 1655MC HC_SMITYPE_TYPE2 + 700 HC_SMITYPE_TYPE3 + 750 HC_SMITYPE_TYPE3 +=================== ===================== -- cgit v1.3.1