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-rw-r--r--Documentation/core-api/printk-formats.rst60
1 files changed, 50 insertions, 10 deletions
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index ecbebf4ca8e7..8ebe46b1af39 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -79,6 +79,18 @@ has the added benefit of providing a unique identifier. On 64-bit machines
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
-------------------------
@@ -86,8 +98,6 @@ Symbols/Function Pointers
%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
@@ -97,14 +107,6 @@ The ``S`` and ``s`` specifiers are used for printing a pointer in symbolic
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
@@ -135,6 +137,20 @@ 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
----------------
@@ -428,6 +444,30 @@ Examples::
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 (struct rtc_time)
-------------------------------