Messages in this thread Patch in this message | | | Date | Fri, 7 Nov 2008 13:51:32 -0800 | From | Randy Dunlap <> | Subject | [PATCH] DOC: add printk-formats.txt |
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From: Randy Dunlap <randy.dunlap@oracle.com>
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> --- Documentation/00-INDEX | 2 ++ Documentation/printk-formats.txt | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+)
--- linux-next-20081107.orig/Documentation/00-INDEX +++ linux-next-20081107/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 --- /dev/null +++ linux-next-20081107/Documentation/printk-formats.txt @@ -0,0 +1,36 @@ +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. + + +Written by Alexey Dobriyan <adobriyan@gmail.com> +Updated by Randy Dunlap <rdunlap@xenotime.net>
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