On Wed, Nov 28, 2018 at 09:12:12PM -0800, Andrew Morton wrote:
> On Fri, 9 Nov 2018 09:34:31 -0800 Daniel Walker <danie...@cisco.com> wrote:
>
> > This code allows architectures to use a generic builtin command line.
> > The state of the builtin command line options across architecture is
> > diverse. On x86 and mips they have pretty much the same code and the
> > code prepends the builtin command line onto the boot loader provided
> > one. On powerpc there is only a builtin override and nothing else.
> >
> > The code in this commit unifies the mips and x86 code into a generic
> > header file under the CONFIG_GENERIC_CMDLINE option. When this
> > option is enabled the architecture can call the cmdline_add_builtin()
> > to add the builtin command line.
>
> I'm not sure what's happened to this and I haven't seen the other two
> patches but...
It's been sitting in -next since the last merge window.
>
> > [maksym.kok...@globallogic.com: fix cmdline_add_builtin() macro]
> > Cc: Daniel Walker <dwal...@fifo99.com>
> > Cc: Daniel Walker <danie...@cisco.com>
> > Cc: xe-linux-exter...@cisco.com
> > Signed-off-by: Daniel Walker <danie...@cisco.com>
> > Signed-off-by: Maksym Kokhan <maksym.kok...@globallogic.com>
>
> Two SOB's is nice, but some reviews and acks would be nicer.
Would love to add some, but no one is reviewing it..
> > --- /dev/null
> > +++ b/include/linux/cmdline.h
> > @@ -0,0 +1,79 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef _LINUX_CMDLINE_H
> > +#define _LINUX_CMDLINE_H
> > +
> > +/*
> > + *
> > + * Copyright (C) 2015. Cisco Systems, Inc.
> > + *
> > + * Generic Append/Prepend cmdline support.
> > + */
> > +
> > +#if defined(CONFIG_GENERIC_CMDLINE) && defined(CONFIG_CMDLINE_BOOL)
> > +
> > +#ifndef CONFIG_CMDLINE_OVERRIDE
> > +/*
> > + * This function will append or prepend a builtin command line to the
> > command
> > + * line provided by the bootloader. Kconfig options can be used to alter
> > + * the behavior of this builtin command line.
> > + * @dest: The destination of the final appended/prepended string
> > + * @src: The starting string or NULL if there isn't one.
> > + * @tmp: temporary space used for prepending
> > + * @length: the maximum length of the strings above.
> > + */
> > +static inline void
> > +_cmdline_add_builtin(char *dest, char *src, char *tmp, unsigned long
> > length)
> > +{
> > + if (src != dest && src != NULL) {
> > + strlcpy(dest, " ", length);
> > + strlcat(dest, src, length);
> > + }
> > +
> > + strlcat(dest, " ", length);
> > +
> > + if (sizeof(CONFIG_CMDLINE_APPEND) > 1)
> > + strlcat(dest, CONFIG_CMDLINE_APPEND, length);
> > +
> > + /*
> > + * You need to convert you old style CONFIG_CMDLINE to use
>
> "your"
>
> > + * the prepend, or append defines. Some architectures use one
>
> "one and"
>
> > + * some use the other. You need to figure out which ones is
>
> "one"
Can fix these..
>
> > + * right for your situation. I would recommend prepending
> > + * because it's the safest (i.e. CONFIG_CMDLINE_PREPEND).
> > + */
> > + BUILD_BUG_ON(sizeof(CONFIG_CMDLINE) != 1);
> > +
> > + if (sizeof(CONFIG_CMDLINE_PREPEND) > 1) {
> > + strlcpy(tmp, CONFIG_CMDLINE_PREPEND, length);
> > + strlcat(tmp, " ", length);
> > + strlcat(tmp, dest, length);
> > + strlcpy(dest, tmp, length);
> > + }
> > +}
>
> And... holy cow. Does this monster really need to be inlined?
>
> > +#define cmdline_add_builtin(dest, src, length)
> > \
> > +{ \
> > + if (sizeof(CONFIG_CMDLINE_PREPEND) > 1) { \
> > + static char cmdline_tmp_space[length] __initdata; \
> > + _cmdline_add_builtin(dest, src, cmdline_tmp_space, length); \
> > + } else { \
> > + _cmdline_add_builtin(dest, src, NULL, length); \
> > + } \
> > +}
>
> And this will generate __initdata storage at each invocation site. Can
> it be redone in real, non-inlined C?
It's intended to be used once, maybe twice, per architecture. Powerpc uses it
twice I think. There's no reason for it to be used more than twice, and it
replaces
code which is similar to the code above. I can' imagine a situation where people
go nuts and start calling this everywhere.
So it seemed easier to just inline it.
Daniel
