Re: [PATCH] arm: Drop deprecated early printk platform options

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi,

> On 13 Sep 2024, at 09:28, Michal Orzel <michal.orzel@xxxxxxx> wrote:
> 
> Hi Bertrand,
> 
> On 13/09/2024 08:54, Bertrand Marquis wrote:
>> 
>> 
>> Hi Michal,
>> 
>>> On 13 Sep 2024, at 08:15, Michal Orzel <michal.orzel@xxxxxxx> wrote:
>>> 
>>> The predefined configurations for early printk have been deprecated for
>>> a sufficient amount of time. Let's finally remove them.
>>> 
>>> Note:
>>> In order not to loose these predefined configurations, I wrote a wiki
>>> page: https://wiki.xenproject.org/wiki/Xen_on_ARM_Early_Printk
>>> 
>>> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>

Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>

>>> ---
>>> docs/misc/arm/early-printk.txt |   4 -
>>> xen/arch/arm/Kconfig.debug     | 155 ++-------------------------------
>>> 2 files changed, 9 insertions(+), 150 deletions(-)
>>> 
>>> diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt
>>> index bc2d65aa2ea3..e6b9124a38e3 100644
>>> --- a/docs/misc/arm/early-printk.txt
>>> +++ b/docs/misc/arm/early-printk.txt
>>> @@ -35,8 +35,4 @@ Other options depends on the driver selected:
>>> 
>>>  - For all other uarts there are no additional options.
>>> 
>>> -As a convenience it is also possible to select from a list of
>>> -predefined configurations available in the list of choice for "Early
>>> -printk" for specific platform.
>>> -
>>> By default early printk is disabled.
>>> diff --git a/xen/arch/arm/Kconfig.debug b/xen/arch/arm/Kconfig.debug
>>> index eec860e88e0b..2fa0acd2a3f1 100644
>>> --- a/xen/arch/arm/Kconfig.debug
>>> +++ b/xen/arch/arm/Kconfig.debug
>>> @@ -13,177 +13,67 @@ choice
>>> Choose one of the UART drivers for early printk, then you'll
>>> have to specify the parameters, like the base address.
>>> 
>>> - Deprecated: Alternatively, there are platform specific options
>>> - which will have default values for the various parameters. But
>>> - such option will soon be removed.
>>> -
>>> config EARLY_UART_CHOICE_8250
>>> select EARLY_UART_8250
>>> bool "Early printk via 8250 UART"
>>> help
>>> Say Y here if you wish the early printk to direct their
>>> - output to a 8250 UART. You can use this option to
>>> - provide the parameters for the 8250 UART rather than
>>> - selecting one of the platform specific options below if
>>> - you know the parameters for the port.
>>> + output to a 8250 UART.
>>> 
>>> - This option is preferred over the platform specific
>>> - options; the platform specific options are deprecated
>>> - and will soon be removed.
>>> config EARLY_UART_CHOICE_CADENCE
>>> select EARLY_UART_CADENCE
>>> depends on ARM_64
>>> bool "Early printk via Cadence UART"
>>> help
>>> Say Y here if you wish the early printk to direct their
>>> - output to a Cadence UART. You can use this option to
>>> - provide the parameters for the Cadence UART rather than
>>> - selecting one of the platform specific options below if
>>> - you know the parameters for the port.
>>> + output to a Cadence UART.
>>> 
>>> - This option is preferred over the platform specific
>>> - options; the platform specific options are deprecated
>>> - and will soon be removed.
>>> config EARLY_UART_CHOICE_EXYNOS4210
>>> select EARLY_UART_EXYNOS4210
>>> depends on ARM_32
>>> bool "Early printk via Exynos4210 UART"
>>> help
>>> Say Y here if you wish the early printk to direct their
>>> - output to a Exynos 4210 UART. You can use this option to
>>> - provide the parameters for the Exynos 4210 UART rather than
>>> - selecting one of the platform specific options below if
>>> - you know the parameters for the port.
>>> + output to a Exynos 4210 UART.
>>> 
>>> - This option is preferred over the platform specific
>>> - options; the platform specific options are deprecated
>>> - and will soon be removed.
>>> config EARLY_UART_CHOICE_IMX_LPUART
>>> select EARLY_UART_IMX_LPUART
>>> depends on ARM_64
>>> bool "Early printk via i.MX LPUART"
>>> help
>>> Say Y here if you wish the early printk to direct their
>>> - output to a i.MX LPUART. You can use this option to
>>> - provide the parameters for the i.MX LPUART rather than
>>> - selecting one of the platform specific options below if
>>> - you know the parameters for the port.
>>> + output to a i.MX LPUART.
>>> +
>>> config EARLY_UART_CHOICE_MESON
>>> select EARLY_UART_MESON
>>> depends on ARM_64
>>> bool "Early printk via MESON UART"
>>> help
>>> Say Y here if you wish the early printk to direct their
>>> - output to a MESON UART. You can use this option to
>>> - provide the parameters for the MESON UART rather than
>>> - selecting one of the platform specific options below if
>>> - you know the parameters for the port.
>>> + output to a MESON UART.
>>> 
>>> - This option is preferred over the platform specific
>>> - options; the platform specific options are deprecated
>>> - and will soon be removed.
>>> config EARLY_UART_CHOICE_MVEBU
>>> select EARLY_UART_MVEBU
>>> depends on ARM_64
>>> bool "Early printk via MVEBU UART"
>>> help
>>> Say Y here if you wish the early printk to direct their
>>> - output to a MVEBU UART. You can use this option to
>>> - provide the parameters for the MVEBU UART rather than
>>> - selecting one of the platform specific options below if
>>> - you know the parameters for the port.
>>> + output to a MVEBU UART.
>>> 
>>> - This option is preferred over the platform specific
>>> - options; the platform specific options are deprecated
>>> - and will soon be removed.
>>> config EARLY_UART_CHOICE_PL011
>>> select EARLY_UART_PL011
>>> bool "Early printk via PL011 UART"
>>> help
>>> Say Y here if you wish the early printk to direct their
>>> - output to a PL011 UART. You can use this option to
>>> - provide the parameters for the PL011 UART rather than
>>> - selecting one of the platform specific options below if
>>> - you know the parameters for the port.
>>> + output to a PL011 UART.
>>> 
>>> - This option is preferred over the platform specific
>>> - options; the platform specific options are deprecated
>>> - and will soon be removed.
>>> config EARLY_UART_CHOICE_SCIF
>>> select EARLY_UART_SCIF
>>> bool "Early printk via SCIF UART"
>>> help
>>> Say Y here if you wish the early printk to direct their
>>> - output to a SCIF UART. You can use this option to
>>> - provide the parameters for the SCIF UART rather than
>>> - selecting one of the platform specific options below if
>>> - you know the parameters for the port.
>>> + output to a SCIF UART.
>>> 
>>> - This option is preferred over the platform specific
>>> - options; the platform specific options are deprecated
>>> - and will soon be removed.
>>> -
>>> - config EARLY_PRINTK_BRCM
>>> - bool "Early printk with 8250 on Broadcom 7445D0 boards with A15 
>>> processors"
>>> - select EARLY_UART_8250
>>> - config EARLY_PRINTK_DRA7
>>> - bool "Early printk with 8250 on DRA7 platform"
>>> - select EARLY_UART_8250
>>> - config EARLY_PRINTK_EXYNOS5250
>>> - bool "Early printk with the second UART on Exynos5250"
>>> - select EARLY_UART_EXYNOS4210
>>> - depends on ARM_32
>>> - config EARLY_PRINTK_FASTMODEL
>>> - bool "Early printk with pl011 on ARM Fastmodel software emulators"
>>> - select EARLY_UART_PL011
>>> - config EARLY_PRINTK_HIKEY960
>>> - bool "Early printk with pl011 with Hikey 960"
>>> - select EARLY_UART_PL011
>>> - config EARLY_PRINTK_JUNO
>>> - bool "Early printk with pl011 on Juno platform"
>>> - select EARLY_UART_PL011
>>> - config EARLY_PRINTK_LAGER
>>> - bool "Early printk with SCIF0 on Renesas Lager board (R-Car H2 processor)"
>>> - select EARLY_UART_SCIF
>>> - config EARLY_PRINTK_MIDWAY
>>> - bool "Early printk with pl011 on Calxeda Midway processors"
>>> - select EARLY_UART_PL011
>>> - config EARLY_PRINTK_MVEBU
>>> - bool "Early printk with MVEBU for Marvell Armada 3700 SoCs"
>>> - select EARLY_UART_MVEBU
>>> - depends on ARM_64
>>> - config EARLY_PRINTK_OMAP5432
>>> - bool "Early printk with UART3 on TI OMAP5432 processors"
>>> - select EARLY_UART_8250
>>> - config EARLY_PRINTK_RCAR3
>>> - bool "Early printk with SCIF2 on Renesas R-Car Gen3 processors"
>>> - select EARLY_UART_SCIF
>>> - config EARLY_PRINTK_SEATTLE
>>> - bool "Early printk with pl011 for AMD Seattle processor"
>>> - select EARLY_UART_PL011
>>> - config EARLY_PRINTK_SUN6I
>>> - bool "Early printk with 8250 on Allwinner A31 processors"
>>> - select EARLY_UART_8250
>>> - config EARLY_PRINTK_SUN7I
>>> - bool "Early printk with 8250 on Allwinner A20 processors"
>>> - select EARLY_UART_8250
>>> - config EARLY_PRINTK_THUNDERX
>>> - bool "Early printk with pl011 for Cavium ThunderX processor"
>>> - select EARLY_UART_PL011
>>> - depends on ARM_64
>>> - config EARLY_PRINTK_VEXPRESS
>>> - bool "Early printk with pl011 for versatile express"
>>> - select EARLY_UART_PL011
>>> - config EARLY_PRINTK_XGENE_MCDIVITT
>>> - bool "Early printk with 820 on Xgene mcdivitt platform"
>>> - select EARLY_UART_8250
>>> - config EARLY_PRINTK_XGENE_STORM
>>> - bool "Early printk with 820 on Xgene storm platform"
>>> - select EARLY_UART_8250
>>> - config EARLY_PRINTK_ZYNQMP
>>> - bool "Early printk with Cadence UART for Xilinx ZynqMP SoCs"
>>> - select EARLY_UART_CADENCE
>>> - depends on ARM_64
>>> endchoice
>>> 
>>> 
>>> @@ -219,25 +109,6 @@ config EARLY_UART_BASE_ADDRESS
>>> depends on EARLY_PRINTK
>>> hex "Early printk, physical base address of debug UART"
>>> range 0x0 0xffffffff if ARM_32
>>> - default 0xF040AB00 if EARLY_PRINTK_BRCM
>>> - default 0x4806A000 if EARLY_PRINTK_DRA7
>>> - default 0x1c090000 if EARLY_PRINTK_FASTMODEL
>>> - default 0x12c20000 if EARLY_PRINTK_EXYNOS5250
>>> - default 0xfff32000 if EARLY_PRINTK_HIKEY960
>>> - default 0x7ff80000 if EARLY_PRINTK_JUNO
>>> - default 0xe6e60000 if EARLY_PRINTK_LAGER
>>> - default 0xfff36000 if EARLY_PRINTK_MIDWAY
>>> - default 0xd0012000 if EARLY_PRINTK_MVEBU
>>> - default 0x48020000 if EARLY_PRINTK_OMAP5432
>>> - default 0xe6e88000 if EARLY_PRINTK_RCAR3
>>> - default 0xe1010000 if EARLY_PRINTK_SEATTLE
>>> - default 0x01c28000 if EARLY_PRINTK_SUN6I
>>> - default 0x01c28000 if EARLY_PRINTK_SUN7I
>>> - default 0x87e024000000 if EARLY_PRINTK_THUNDERX
>>> - default 0x1c090000 if EARLY_PRINTK_VEXPRESS
>>> - default 0x1c021000 if EARLY_PRINTK_XGENE_MCDIVITT
>>> - default 0x1c020000 if EARLY_PRINTK_XGENE_STORM
>>> - default 0xff000000 if EARLY_PRINTK_ZYNQMP
>> 
>> Shouldn't we put a default 0 value here ?
> No, we should not. It's done like that on purpose to trigger build error
> if user enables early printk but forgets to specify an address. Adding 
> default 0
> would remove this guard behavior.
> 

Ok makes sense.

>> 
>>> 
>>> config EARLY_UART_PL011_BAUD_RATE
>>> depends on EARLY_UART_PL011
>>> @@ -250,7 +121,6 @@ config EARLY_UART_PL011_BAUD_RATE
>>> not try to initialize the UART, so that bootloader or firmware
>>> settings can be used for maximum compatibility.
>>> 
>>> - default 115200 if EARLY_PRINTK_FASTMODEL
>>> default 0
>>> 
>>> config EARLY_UART_PL011_MMIO32
>>> @@ -274,13 +144,6 @@ config EARLY_UART_8250_REG_SHIFT
>>> 
>>> Default to 0.
>>> 
>>> - default 2 if EARLY_PRINTK_BRCM
>>> - default 2 if EARLY_PRINTK_DRA7
>>> - default 2 if EARLY_PRINTK_OMAP5432
>>> - default 2 if EARLY_PRINTK_SUN6I
>>> - default 2 if EARLY_PRINTK_SUN7I
>>> - default 2 if EARLY_PRINTK_XGENE_MCDIVITT
>>> - default 2 if EARLY_PRINTK_XGENE_STORM
>>> default 0
>> 
>> Seeing that all know example are setting this to 2, wouldn't it
>> make sense to change the default to 2 ?
> It would be a change in behavior and would not fit the purpose of this patch.
> Also, the EARLY_UART_8250_REG_SHIFT Kconfig help mentions 0 as a default.
> There might be platforms 8250 based where we don't know the correct reg shift 
> value.
> Better not to make any assumptions.
> 

Ok.

> ~Michal