Re: [PATCH v3] powerpc: Support CMDLINE_EXTEND

From: Chris Packham
Date: Thu Sep 26 2019 - 19:56:53 EST


Hi All,

On Fri, 2019-08-02 at 06:40 +0200, Christophe Leroy wrote:
>
> Le 02/08/2019 Ã 00:50, Chris Packham a Ãcrit :
> > Bring powerpc in line with other architectures that support extending or
> > overriding the bootloader provided command line.
> >
> > The current behaviour is most like CMDLINE_FROM_BOOTLOADER where the
> > bootloader command line is preferred but the kernel config can provide a
> > fallback so CMDLINE_FROM_BOOTLOADER is the default. CMDLINE_EXTEND can
> > be used to append the CMDLINE from the kernel config to the one provided
> > by the bootloader.
> >
> > Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
>
> Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxx>

I see this hasn't hit Linus's tree is it waiting for me to do something
or just fallen off the radar?

>
> > ---
> > Changes in v3:
> > - don't use BUG_ON in prom_strlcat
> > - rearrange things to eliminate prom_strlcpy
> >
> > Changes in v2:
> > - incorporate ideas from Christope's patch https://patchwork.ozlabs.org/patch/1074126/
> > - support CMDLINE_FORCE
> >
> > arch/powerpc/Kconfig | 20 +++++++++++++++++-
> > arch/powerpc/kernel/prom_init.c | 36 ++++++++++++++++++++++-----------
> > 2 files changed, 43 insertions(+), 13 deletions(-)
> >
> > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> > index 77f6ebf97113..d413fe1b4058 100644
> > --- a/arch/powerpc/Kconfig
> > +++ b/arch/powerpc/Kconfig
> > @@ -852,15 +852,33 @@ config CMDLINE
> > some command-line options at build time by entering them here. In
> > most cases you will need to specify the root device here.
> >
> > +choice
> > + prompt "Kernel command line type" if CMDLINE != ""
> > + default CMDLINE_FROM_BOOTLOADER
> > +
> > +config CMDLINE_FROM_BOOTLOADER
> > + bool "Use bootloader kernel arguments if available"
> > + help
> > + Uses the command-line options passed by the boot loader. If
> > + the boot loader doesn't provide any, the default kernel command
> > + string provided in CMDLINE will be used.
> > +
> > +config CMDLINE_EXTEND
> > + bool "Extend bootloader kernel arguments"
> > + help
> > + The command-line arguments provided by the boot loader will be
> > + appended to the default kernel command string.
> > +
> > config CMDLINE_FORCE
> > bool "Always use the default kernel command string"
> > - depends on CMDLINE_BOOL
> > help
> > Always use the default kernel command string, even if the boot
> > loader passes other arguments to the kernel.
> > This is useful if you cannot or don't want to change the
> > command-line options your boot loader passes to the kernel.
> >
> > +endchoice
> > +
> > config EXTRA_TARGETS
> > string "Additional default image types"
> > help
> > diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
> > index 514707ef6779..1c7010cc6ec9 100644
> > --- a/arch/powerpc/kernel/prom_init.c
> > +++ b/arch/powerpc/kernel/prom_init.c
> > @@ -298,16 +298,24 @@ static char __init *prom_strstr(const char *s1, const char *s2)
> > return NULL;
> > }
> >
> > -static size_t __init prom_strlcpy(char *dest, const char *src, size_t size)
> > -{
> > - size_t ret = prom_strlen(src);
> > +static size_t __init prom_strlcat(char *dest, const char *src, size_t count)
> > +{
> > + size_t dsize = prom_strlen(dest);
> > + size_t len = prom_strlen(src);
> > + size_t res = dsize + len;
> > +
> > + /* This would be a bug */
> > + if (dsize >= count)
> > + return count;
> > +
> > + dest += dsize;
> > + count -= dsize;
> > + if (len >= count)
> > + len = count-1;
> > + memcpy(dest, src, len);
> > + dest[len] = 0;
> > + return res;
> >
> > - if (size) {
> > - size_t len = (ret >= size) ? size - 1 : ret;
> > - memcpy(dest, src, len);
> > - dest[len] = '\0';
> > - }
> > - return ret;
> > }
> >
> > #ifdef CONFIG_PPC_PSERIES
> > @@ -759,10 +767,14 @@ static void __init early_cmdline_parse(void)
> >
> > prom_cmd_line[0] = 0;
> > p = prom_cmd_line;
> > - if ((long)prom.chosen > 0)
> > +
> > + if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && (long)prom.chosen > 0)
> > l = prom_getprop(prom.chosen, "bootargs", p, COMMAND_LINE_SIZE-1);
> > - if (IS_ENABLED(CONFIG_CMDLINE_BOOL) && (l <= 0 || p[0] == '\0')) /* dbl check */
> > - prom_strlcpy(prom_cmd_line, CONFIG_CMDLINE, sizeof(prom_cmd_line));
> > +
> > + if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || l <= 0 || p[0] == '\0')
> > + prom_strlcat(prom_cmd_line, " " CONFIG_CMDLINE,
> > + sizeof(prom_cmd_line));
> > +
> > prom_printf("command line: %s\n", prom_cmd_line);
> >
> > #ifdef CONFIG_PPC64
> >