From a5969cabbb4660eab42b6ef0412cbbd1200cf14d Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Sat, 12 Oct 2024 07:10:09 +0000
Subject: [PATCH] 修改led为gpio
---
kernel/Documentation/core-api/printk-formats.rst | 131 +++++++++++++++++++++++++++++++++++++------
1 files changed, 112 insertions(+), 19 deletions(-)
diff --git a/kernel/Documentation/core-api/printk-formats.rst b/kernel/Documentation/core-api/printk-formats.rst
index 25dc591..6d26c5c 100644
--- a/kernel/Documentation/core-api/printk-formats.rst
+++ b/kernel/Documentation/core-api/printk-formats.rst
@@ -2,6 +2,8 @@
How to get printk format specifiers right
=========================================
+.. _printk-specifiers:
+
:Author: Randy Dunlap <rdunlap@infradead.org>
:Author: Andrew Murray <amurray@mpc-data.co.uk>
@@ -13,6 +15,10 @@
If variable is of Type, use printk format specifier:
------------------------------------------------------------
+ char %d or %x
+ unsigned char %u or %x
+ short int %d or %x
+ unsigned short int %u or %x
int %d or %x
unsigned int %u or %x
long %ld or %lx
@@ -21,6 +27,10 @@
unsigned long long %llu or %llx
size_t %zu or %zx
ssize_t %zd or %zx
+ s8 %d or %x
+ u8 %u or %x
+ s16 %d or %x
+ u16 %u or %x
s32 %d or %x
u32 %u or %x
s64 %lld or %llx
@@ -50,6 +60,14 @@
before printing. The kernel also supports extended specifiers for printing
pointers of different types.
+Some of the extended specifiers print the data on the given address instead
+of printing the address itself. In this case, the following error messages
+might be printed instead of the unreachable information::
+
+ (null) data on plain NULL address
+ (efault) data on invalid address
+ (einval) invalid data on a valid address
+
Plain Pointers
--------------
@@ -63,6 +81,18 @@
the first 32 bits are zeroed. The kernel will print ``(ptrval)`` until it
gathers enough entropy. If you *really* want the address see %px below.
+Error Pointers
+--------------
+
+::
+
+ %pe -ENOSPC
+
+For printing error pointers (i.e. a pointer for which IS_ERR() is true)
+as a symbolic error name. Error values for which no symbolic name is
+known are printed in decimal, while a non-ERR_PTR passed as the
+argument to %pe gets treated as ordinary %p.
+
Symbols/Function Pointers
-------------------------
@@ -70,8 +100,6 @@
%pS versatile_init+0x0/0x110
%ps versatile_init
- %pF versatile_init+0x0/0x110
- %pf versatile_init
%pSR versatile_init+0x9/0x110
(with __builtin_extract_return_addr() translation)
%pB prev_fn_of_versatile_init+0x88/0x88
@@ -81,18 +109,24 @@
format. They result in the symbol name with (S) or without (s)
offsets. If KALLSYMS are disabled then the symbol address is printed instead.
-Note, that the ``F`` and ``f`` specifiers are identical to ``S`` (``s``)
-and thus deprecated. We have ``F`` and ``f`` because on ia64, ppc64 and
-parisc64 function pointers are indirect and, in fact, are function
-descriptors, which require additional dereferencing before we can lookup
-the symbol. As of now, ``S`` and ``s`` perform dereferencing on those
-platforms (when needed), so ``F`` and ``f`` exist for compatibility
-reasons only.
-
The ``B`` specifier results in the symbol name with offsets and should be
used when printing stack backtraces. The specifier takes into
consideration the effect of compiler optimisations which may occur
when tail-calls are used and marked with the noreturn GCC attribute.
+
+Probed Pointers from BPF / tracing
+----------------------------------
+
+::
+
+ %pks kernel string
+ %pus user string
+
+The ``k`` and ``u`` specifiers are used for printing prior probed memory from
+either kernel memory (k) or user memory (u). The subsequent ``s`` specifier
+results in printing a string. For direct use in regular vsnprintf() the (k)
+and (u) annotation is ignored, however, when used out of BPF's bpf_trace_printk(),
+for example, it reads the memory it is pointing to without faulting.
Kernel Pointers
---------------
@@ -103,7 +137,7 @@
For printing kernel pointers which should be hidden from unprivileged
users. The behaviour of %pK depends on the kptr_restrict sysctl - see
-Documentation/sysctl/kernel.txt for more details.
+Documentation/admin-guide/sysctl/kernel.rst for more details.
Unmodified Addresses
--------------------
@@ -118,6 +152,20 @@
equivalent to %lx (or %lu). %px is preferred because it is more uniquely
grep'able. If in the future we need to modify the way the kernel handles
printing pointers we will be better equipped to find the call sites.
+
+Pointer Differences
+-------------------
+
+::
+
+ %td 2560
+ %tx a00
+
+For printing the pointer differences, use the %t modifier for ptrdiff_t.
+
+Example::
+
+ printk("test: difference between pointers: %td\n", ptr2 - ptr1);
Struct Resources
----------------
@@ -269,7 +317,7 @@
The additional ``c`` specifier can be used with the ``I`` specifier to
print a compressed IPv6 address as described by
-http://tools.ietf.org/html/rfc5952
+https://tools.ietf.org/html/rfc5952
Passed by reference.
@@ -293,7 +341,7 @@
flowinfo a ``/`` and scope a ``%``, each followed by the actual value.
In case of an IPv6 address the compressed IPv6 address as described by
-http://tools.ietf.org/html/rfc5952 is being used if the additional
+https://tools.ietf.org/html/rfc5952 is being used if the additional
specifier ``c`` is given. The IPv6 address is surrounded by ``[``, ``]`` in
case of additional specifiers ``p``, ``f`` or ``s`` as suggested by
https://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-07
@@ -376,15 +424,15 @@
Passed by reference.
-kobjects
---------
+Device tree nodes
+-----------------
::
%pOF[fnpPcCF]
-For printing kobject based structs (device nodes). Default behaviour is
+For printing device tree node structures. Default behaviour is
equivalent to %pOFf.
- f - device node full_name
@@ -412,6 +460,52 @@
Passed by reference.
+Fwnode handles
+--------------
+
+::
+
+ %pfw[fP]
+
+For printing information on fwnode handles. The default is to print the full
+node name, including the path. The modifiers are functionally equivalent to
+%pOF above.
+
+ - f - full name of the node, including the path
+ - P - the name of the node including an address (if there is one)
+
+Examples (ACPI)::
+
+ %pfwf \_SB.PCI0.CIO2.port@1.endpoint@0 - Full node name
+ %pfwP endpoint@0 - Node name
+
+Examples (OF)::
+
+ %pfwf /ocp@68000000/i2c@48072000/camera@10/port/endpoint - Full name
+ %pfwP endpoint - Node name
+
+Time and date
+-------------
+
+::
+
+ %pt[RT] YYYY-mm-ddTHH:MM:SS
+ %pt[RT]d YYYY-mm-dd
+ %pt[RT]t HH:MM:SS
+ %pt[RT][dt][r]
+
+For printing date and time as represented by::
+
+ R struct rtc_time structure
+ T time64_t type
+
+in human readable format.
+
+By default year will be incremented by 1900 and month by 1.
+Use %pt[RT]r (raw) to suppress this behaviour.
+
+Passed by reference.
+
struct clk
----------
@@ -420,9 +514,8 @@
%pC pll1
%pCn pll1
-For printing struct clk structures. %pC and %pCn print the name
-(Common Clock Framework) or address (legacy clock framework) of the
-structure.
+For printing struct clk structures. %pC and %pCn print the name of the clock
+(Common Clock Framework) or a unique 32-bit ID (legacy clock framework).
Passed by reference.
--
Gitblit v1.6.2