diff options
| author | Randy Dunlap <randy.dunlap@oracle.com> | 2008-11-12 13:26:55 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-11-12 17:17:17 -0800 |
| commit | b67ad18b06701b77ca8bfe9bb760c5c9e765e3cf (patch) | |
| tree | f0b87e5fceec394f096e932db1f0a5fb7b104f50 /Documentation | |
| parent | b76f90b526737070302a127c710263e2ac707676 (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-INDEX | 2 | ||||
| -rw-r--r-- | Documentation/printk-formats.txt | 35 |
2 files changed, 37 insertions, 0 deletions
diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index edef85ce119..50f99eab0e1 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -290,6 +290,8 @@ powerpc/ - directory with info on using Linux with the PowerPC. preempt-locking.txt - info on locking under a preemptive kernel. +printk-formats.txt + - how to get printk format specifiers right prio_tree.txt - info on radix-priority-search-tree use for indexing vmas. ramdisk.txt diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt new file mode 100644 index 00000000000..1b5a5ddbc3e --- /dev/null +++ b/Documentation/printk-formats.txt @@ -0,0 +1,35 @@ +If variable is of Type, use printk format specifier: +--------------------------------------------------------- + int %d or %x + unsigned int %u or %x + long %ld or %lx + unsigned long %lu or %lx + long long %lld or %llx + unsigned long long %llu or %llx + size_t %zu or %zx + ssize_t %zd or %zx + +Raw pointer value SHOULD be printed with %p. + +u64 SHOULD be printed with %llu/%llx, (unsigned long long): + + printk("%llu", (unsigned long long)u64_var); + +s64 SHOULD be printed with %lld/%llx, (long long): + + printk("%lld", (long long)s64_var); + +If <type> is dependent on a config option for its size (e.g., sector_t, +blkcnt_t, phys_addr_t, resource_size_t) or is architecture-dependent +for its size (e.g., tcflag_t), use a format specifier of its largest +possible type and explicitly cast to it. Example: + + printk("test: sector number/total blocks: %llu/%llu\n", + (unsigned long long)sector, (unsigned long long)blockcount); + +Reminder: sizeof() result is of type size_t. + +Thank you for your cooperation and attention. + + +By Randy Dunlap <rdunlap@xenotime.net> |