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Date:   Mon, 7 Jan 2019 14:43:57 +0000
From:   Mark Rutland <mark.rutland@arm.com>
To:     Anders Roxell <anders.roxell@linaro.org>
Cc:     linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
        will.deacon@arm.com, arnd@arndb.de, mingo@redhat.com,
        rostedt@goodmis.org, akpm@linux-foundation.org, broonie@kernel.org
Subject: Re: [RFC PATCH 3/3] arm64: add a new config option KTEST_RUNNABLE
Message-ID: <20190107144356.GB46743@lakrids.cambridge.arm.com>
References: <20181213122910.24193-1-anders.roxell@linaro.org>
 <20181213122910.24193-4-anders.roxell@linaro.org>
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Hi,

As a general thing, please Cc LAKML on patches for arm64.

On Thu, Dec 13, 2018 at 01:29:10PM +0100, Anders Roxell wrote:
> With this new config option, we can boot a allmodconfig kernel in qemu.
> Config options SERIAL_AMBA_PL011, SERIAL_AMBA_PL011_CONSOLE, UNIX needs
> to be enabled in order to get a console. Options like CPU_BIG_ENDIAN,
> CMDLINE_FORCE, CMDLINE_OVERRIDE and HVC_DCC needs to be disabled.
> 
> Co-developed-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
> ---
>  arch/arm64/Kconfig      | 8 ++++++++
>  drivers/tty/hvc/Kconfig | 1 +
>  init/Kconfig            | 1 +
>  3 files changed, 10 insertions(+)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 1f52362f8d99..bb17ccb7bab2 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -292,6 +292,12 @@ config ARCH_SUPPORTS_UPROBES
>  config ARCH_PROC_KCORE_TEXT
>  	def_bool y
>  
> +config KTEST_RUNNABLE
> +	bool "Test build kernels that run in qemu for ktest"
> +	select SERIAL_AMBA_PL011
> +	select SERIAL_AMBA_PL011_CONSOLE
> +	select UNIX
> +

As Mark Brown points out, the PL011 bits are platform-specific, and
don't directly relate to ktest.

The UNIX part is simply because that can be built as a module.

Is it possible to use an allyesconfig rather than an allmodconfig? That
would leave all relevant options built-in.

> diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
> index 4293c172e120..44e23c2388bd 100644
> --- a/drivers/tty/hvc/Kconfig
> +++ b/drivers/tty/hvc/Kconfig
> @@ -82,6 +82,7 @@ config HVC_UDBG
>  config HVC_DCC
>         bool "ARM JTAG DCC console"
>         depends on ARM || ARM64
> +	depends on !KTEST_RUNNABLE
>         select HVC_DRIVER
>         help
>           This console uses the JTAG DCC on ARM to create a console under the HVC

... this is just a hack around the DCC driver being dodgy.

We should fix that to only probe if explicitly requested at run-time via
a command line argument.

Thanks,
Mark.