On Mon, May 18, 2020 at 10:09:34PM -0700, Joe Perches wrote:
> 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.
>
>
>
Should it use pr_cont to print the subsequent lines?
