mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-05 16:37:50 +00:00
42 lines
1.8 KiB
ReStructuredText
42 lines
1.8 KiB
ReStructuredText
|
.. SPDX-License-Identifier: GPL-2.0
|
||
|
|
|
||
|
|
RISC-V Hardware Probing Interface
|
||
|
|
---------------------------------
|
||
|
|
|
||
|
|
The RISC-V hardware probing interface is based around a single syscall, which
|
||
|
|
is defined in <asm/hwprobe.h>::
|
||
|
|
|
||
|
|
struct riscv_hwprobe {
|
||
|
|
__s64 key;
|
||
|
|
__u64 value;
|
||
|
|
};
|
||
|
|
|
||
|
|
long sys_riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
|
||
|
|
size_t cpu_count, cpu_set_t *cpus,
|
||
|
|
unsigned int flags);
|
||
|
|
|
||
|
|
The arguments are split into three groups: an array of key-value pairs, a CPU
|
||
|
|
set, and some flags. The key-value pairs are supplied with a count. Userspace
|
||
|
|
must prepopulate the key field for each element, and the kernel will fill in the
|
||
|
|
value if the key is recognized. If a key is unknown to the kernel, its key field
|
||
|
|
will be cleared to -1, and its value set to 0. The CPU set is defined by
|
||
|
|
CPU_SET(3). For value-like keys (eg. vendor/arch/impl), the returned value will
|
||
|
|
be only be valid if all CPUs in the given set have the same value. Otherwise -1
|
||
|
|
will be returned. For boolean-like keys, the value returned will be a logical
|
||
|
|
AND of the values for the specified CPUs. Usermode can supply NULL for cpus and
|
||
|
|
0 for cpu_count as a shortcut for all online CPUs. There are currently no flags,
|
||
|
|
this value must be zero for future compatibility.
|
||
|
|
|
||
|
|
On success 0 is returned, on failure a negative error code is returned.
|
||
|
|
|
||
|
|
The following keys are defined:
|
||
|
|
|
||
|
|
* :c:macro:`RISCV_HWPROBE_KEY_MVENDORID`: Contains the value of ``mvendorid``,
|
||
|
|
as defined by the RISC-V privileged architecture specification.
|
||
|
|
|
||
|
|
* :c:macro:`RISCV_HWPROBE_KEY_MARCHID`: Contains the value of ``marchid``, as
|
||
|
|
defined by the RISC-V privileged architecture specification.
|
||
|
|
|
||
|
|
* :c:macro:`RISCV_HWPROBE_KEY_MIMPLID`: Contains the value of ``mimplid``, as
|
||
|
|
defined by the RISC-V privileged architecture specification.
|