Messages in this thread | | | From | Arvind Sankar <> | Date | Tue, 19 May 2020 10:34:28 -0400 | Subject | Re: [PATCH] init/main.c: Print all command line when boot |
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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 <wangchenggang@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-joe@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?
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