Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2] powerpc: Support CMDLINE_EXTEND | From | Christophe Leroy <> | Date | Thu, 1 Aug 2019 08:14:29 +0200 |
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Le 01/08/2019 à 04:12, Chris Packham a écrit : > 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@alliedtelesis.co.nz> > --- > While I'm at it does anyone think it's worth getting rid of the default CMDLINE > value if CMDLINE_BOOL and maybe CMDLINE_BOOL? Every defconfig in the kernel > that sets CMDLINE_BOOL=y also sets CMDLINE to something other than > "console=ttyS0,9600 console=tty0 root=/dev/sda2". Removing CMDLINE_BOOL and > unconditionally setting the default value of CMDLINE to "" would clean up the > Kconfig even more.
Note https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cbe46bd4f5104552b612505b73d366f66efc2341 which is already a step forward.
I guess that default is for users selecting this option manually to get a first sensitive CMDLINE. But is it really worth it ?
> > Changes in v2: > - incorporate ideas from Christope's patch https://patchwork.ozlabs.org/patch/1074126/ > > arch/powerpc/Kconfig | 20 +++++++++++++++++++- > arch/powerpc/kernel/prom_init.c | 26 +++++++++++++++++++++++++- > 2 files changed, 44 insertions(+), 2 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..df29f141dbd2 100644 > --- a/arch/powerpc/kernel/prom_init.c > +++ b/arch/powerpc/kernel/prom_init.c > @@ -310,6 +310,25 @@ static size_t __init prom_strlcpy(char *dest, const char *src, size_t size) > return ret; > } > > +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 */ > + BUG_ON(dsize >= count);
Has you pointed in another mail, BUG_ON() should be avoided here. I guess if the destination is already full, just return count:
if (dsize >= count) return count;
> + > + dest += dsize; > + count -= dsize; > + if (len >= count) > + len = count-1; > + memcpy(dest, src, len); > + dest[len] = 0; > + return res; > + > +} > + > #ifdef CONFIG_PPC_PSERIES > static int __init prom_strtobool(const char *s, bool *res) > { > @@ -761,8 +780,13 @@ static void __init early_cmdline_parse(void) > p = prom_cmd_line; > if ((long)prom.chosen > 0) > l = prom_getprop(prom.chosen, "bootargs", p, COMMAND_LINE_SIZE-1);
The above is pointless in case CONFIG_CMDLINE_FORCE is selected.
> - if (IS_ENABLED(CONFIG_CMDLINE_BOOL) && (l <= 0 || p[0] == '\0')) /* dbl check */ > + > + if (IS_ENABLED(CONFIG_CMDLINE_FORCE) || l <= 0 || p[0] == '\0') > prom_strlcpy(prom_cmd_line, CONFIG_CMDLINE, sizeof(prom_cmd_line));
If we can ensure that prom_cmd_line remains empty when CONFIG_CMDLINE_FORCE is selected (see above comment), then prom_strlcat() can be used in lieu of prom_strlcpy()
> + else if (IS_ENABLED(CONFIG_CMDLINE_EXTEND)) > + prom_strlcat(prom_cmd_line, " " CONFIG_CMDLINE, > + sizeof(prom_cmd_line)); > + > prom_printf("command line: %s\n", prom_cmd_line); > > #ifdef CONFIG_PPC64 >
Christophe
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