aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation
diff options
context:
space:
mode:
authorRandy Dunlap <randy.dunlap@oracle.com>2008-11-12 16:26:55 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2008-11-12 20:17:17 -0500
commitb67ad18b06701b77ca8bfe9bb760c5c9e765e3cf (patch)
treef0b87e5fceec394f096e932db1f0a5fb7b104f50 /Documentation
parentb76f90b526737070302a127c710263e2ac707676 (diff)
DOC: add printk-formats.txt
Add printk-formats.txt so that we don't have to keep fixing the same things over and over again. <wishful thinking> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/00-INDEX2
-rw-r--r--Documentation/printk-formats.txt35
2 files changed, 37 insertions, 0 deletions
diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX
index edef85ce1195..50f99eab0e1f 100644
--- a/Documentation/00-INDEX
+++ b/Documentation/00-INDEX
@@ -290,6 +290,8 @@ powerpc/
290 - directory with info on using Linux with the PowerPC. 290 - directory with info on using Linux with the PowerPC.
291preempt-locking.txt 291preempt-locking.txt
292 - info on locking under a preemptive kernel. 292 - info on locking under a preemptive kernel.
293printk-formats.txt
294 - how to get printk format specifiers right
293prio_tree.txt 295prio_tree.txt
294 - info on radix-priority-search-tree use for indexing vmas. 296 - info on radix-priority-search-tree use for indexing vmas.
295ramdisk.txt 297ramdisk.txt
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
new file mode 100644
index 000000000000..1b5a5ddbc3ef
--- /dev/null
+++ b/Documentation/printk-formats.txt
@@ -0,0 +1,35 @@
1If variable is of Type, use printk format specifier:
2---------------------------------------------------------
3 int %d or %x
4 unsigned int %u or %x
5 long %ld or %lx
6 unsigned long %lu or %lx
7 long long %lld or %llx
8 unsigned long long %llu or %llx
9 size_t %zu or %zx
10 ssize_t %zd or %zx
11
12Raw pointer value SHOULD be printed with %p.
13
14u64 SHOULD be printed with %llu/%llx, (unsigned long long):
15
16 printk("%llu", (unsigned long long)u64_var);
17
18s64 SHOULD be printed with %lld/%llx, (long long):
19
20 printk("%lld", (long long)s64_var);
21
22If <type> is dependent on a config option for its size (e.g., sector_t,
23blkcnt_t, phys_addr_t, resource_size_t) or is architecture-dependent
24for its size (e.g., tcflag_t), use a format specifier of its largest
25possible type and explicitly cast to it. Example:
26
27 printk("test: sector number/total blocks: %llu/%llu\n",
28 (unsigned long long)sector, (unsigned long long)blockcount);
29
30Reminder: sizeof() result is of type size_t.
31
32Thank you for your cooperation and attention.
33
34
35By Randy Dunlap <rdunlap@xenotime.net>