Re: [PATCH v3 05/17] arm: Convert to GENERIC_CMDLINE

+Nico who added the line in question.

On Fri, Mar 26, 2021 at 9:50 AM Christophe Leroy
[off-list ref] wrote:

Le 26/03/2021 à 16:47, Rob Herring a écrit :

quoted

On Fri, Mar 26, 2021 at 7:44 AM Christophe Leroy
[off-list ref] wrote:

quoted

This converts the architecture to GENERIC_CMDLINE.

Signed-off-by: Christophe Leroy <redacted>
---
  arch/arm/Kconfig              | 38 +----------------------------------
  arch/arm/kernel/atags_parse.c | 15 +++++---------
  2 files changed, 6 insertions(+), 47 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 5da96f5df48f..67bc75f2da81 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig

@@ -50,6 +50,7 @@ config ARM
         select GENERIC_ARCH_TOPOLOGY if ARM_CPU_TOPOLOGY
         select GENERIC_ATOMIC64 if CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI
         select GENERIC_CLOCKEVENTS_BROADCAST if SMP
+       select GENERIC_CMDLINE if ATAGS

Don't we need this enabled for !ATAGS (i.e. DT boot)?

Can we always enable GENERIC_CMDLINE for OF_EARLY_FLATTREE?

Don't know.

Today ARM has:

choice
        prompt "Kernel command line type" if CMDLINE != ""
        default CMDLINE_FROM_BOOTLOADER
        depends on ATAGS

I think that's a mistake. In a DT only case (no ATAGS), we'll get
different behaviour (in fdt.c) depending if CONFIG_ATAGS is enabled or
not. Note that at the time (2012) the above was added, the DT code
only supported CONFIG_CMDLINE and CONFIG_CMDLINE_FORCE.
CONFIG_CMDLINE_EXTEND was only added in 2016. And that has different
behavior for ATAGS vs. DT. In summary, it's a mess. We should drop the
depends either before this patch or just as part of this patch IMO.
I'd go with the latter given CONFIG_ATAGS is default y and enabled for
common configs. Without that, it looks like CONFIG_CMDLINE disappears
from menuconfig for at91_dt_defconfig.

Also, I think this code should be refactored a bit to eliminate
default_command_line. Instead, we should just save a pointer to the
ATAGS command line string, and then call cmdline_build here instead of
doing the extra copy:

        /* parse_early_param needs a boot_command_line */
        strlcpy(boot_command_line, from, COMMAND_LINE_SIZE);

Rob