On Mon, 2020-05-18 at 20:44 -0700, Andrew Morton wrote: > On Tue, 19 May 2020 11:29:46 +0800 王程刚 <wangchengg...@vivo.com> wrote: > > > Function pr_notice print max length maybe less than the command line length, > > need more times to print all. > > For example, arm64 has 2048 bytes command line length, but printk maximum > > length is only 1024 bytes. > > I can see why that might be a problem! > > > --- a/init/main.c > > +++ b/init/main.c > > @@ -825,6 +825,16 @@ void __init __weak arch_call_rest_init(void) > > rest_init(); > > } > > > > +static void __init print_cmdline(void) > > +{ > > + const char *prefix = "Kernel command line: "; > > const char prefix[] = "..."; > > might generate slightly more efficient code. > > > + int len = -strlen(prefix); > > hm, tricky. What the heck does printk() actually return to the caller? > Seems that we forgot to document this, and there are so many different > paths which a printk call can take internally that I'm not confident > that they all got it right!
There is no use of the return value of any pr_<level> or dev_<level> or netdev_<level) in the kernel. All the pr_<level> mechanisms (as functions) should return void. https://lore.kernel.org/lkml/1466739971-30399-1-git-send-email-...@perches.com/ > > + len += pr_notice("%s%s\n", prefix, boot_command_line); > > + while (boot_command_line[len]) > > + len += pr_notice("%s\n", &boot_command_line[len]); > > +} More likely it'd be better to use a strlen(boot_command_line) and perhaps do something like print multiple lines with args using strchr(, ' ') at some largish value, say 132 or 256 chars maximum per line.