Re: [PATCH 3/3] ACPI: ARM64: support for ACPI_TABLE_UPGRADE

[Mark Rutland <mark.rutland@arm.com>]

On Tue, May 17, 2016 at 03:06:03PM +0300, Aleksey Makarov wrote:
> From: Jon Masters <jcm@redhat.com>
> 
> This patch adds support for ACPI_TABLE_UPGRADE for ARM64

This feels like a tool to paper over problems rather than solve them.

If vendors are shipping horrendously broken tables today, clearly no
software has ever really supported them. So why add workarounds?

Why is this necessary? Is there a particular case for this, or is this
just for parity with x86?

IMO it would be better to put pressure on vendors to fix their FW and
provide sensible OS-agnostic update mechanisms.

> To access initrd image we need to move initialization
> of linear mapping a bit earlier.
> 
> Signed-off-by: Jon Masters <jcm@redhat.com>
> Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org>
> ---
>  arch/arm64/kernel/setup.c |  6 ++++--
>  drivers/acpi/Kconfig      |  2 +-
>  drivers/acpi/tables.c     | 10 +++++++++-
>  3 files changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index feab2ee..1d5e24f 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -261,11 +261,13 @@ void __init setup_arch(char **cmdline_p)
>  	efi_init();
>  	arm64_memblock_init();
>  
> +	paging_init();
> +
> +	early_initrd_acpi_init();

Do we actually need full paging up here?

Why can we not use fixmap based copying as we do for the other cases
prior to paging_init?

> +
>  	/* Parse the ACPI tables for possible boot-time configuration */
>  	acpi_boot_table_init();
>  
> -	paging_init();
> -
>  	if (acpi_disabled)
>  		unflatten_device_tree();
>  
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index c204344..ec694c0 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -313,7 +313,7 @@ config ACPI_CUSTOM_DSDT
>  
>  config ACPI_TABLE_UPGRADE
>  	bool "Allow upgrading ACPI tables via initrd"
> -	depends on BLK_DEV_INITRD && X86
> +	depends on BLK_DEV_INITRD && (X86 || ARM64)
>  	default y
>  	help

Perhaps ARCH_HAS_ACPI_TABLE_UPGRADE?

>  	  This option provides functionality to upgrade arbitrary ACPI tables
> diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
> index 82be84a..c35034d8 100644
> --- a/drivers/acpi/tables.c
> +++ b/drivers/acpi/tables.c
> @@ -482,6 +482,14 @@ static DECLARE_BITMAP(acpi_initrd_installed, NR_ACPI_INITRD_TABLES);
>  
>  #define MAP_CHUNK_SIZE   (NR_FIX_BTMAPS << PAGE_SHIFT)
>  
> +#if defined(CONFIG_X86)
> +#define MAX_PHYS_ACPI_TABLES (max_low_pfn_mapped << PAGE_SHIFT)
> +#elif defined(CONFIG_ARM64)
> +#define MAX_PHYS_ACPI_TABLES PFN_PHYS(max_pfn)
> +#else
> +#error "MAX_PHYS_ACPI_TABLES is not defiend for this architecture"
> +#endif

s/defiend/defined/

This should be defined in an arch-specific header if it is actually
arch-specific.

Thanks,
Mark.

> +
>  static void __init acpi_table_initrd_init(void *data, size_t size)
>  {
>  	int sig, no, table_nr = 0, total_offset = 0;
> @@ -541,7 +549,7 @@ static void __init acpi_table_initrd_init(void *data, size_t size)
>  		return;
>  
>  	acpi_tables_addr =
> -		memblock_find_in_range(0, max_low_pfn_mapped << PAGE_SHIFT,
> +		memblock_find_in_range(0, MAX_PHYS_ACPI_TABLES,
>  				       all_tables_size, PAGE_SIZE);
>  	if (!acpi_tables_addr) {
>  		WARN_ON(1);
> -- 
> 2.8.2
>