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Date: Sat, 30 Dec 2023 15:40:51 +0100
From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] MIPS: Enable SPARSEMEM option unconditionally on
 64BIT
Message-ID: <ZZAr84wveFdBZ+hm@alpha.franken.de>
References: <20231028-mm-v1-0-45377cd158cf@flygoat.com>
 <20231028-mm-v1-1-45377cd158cf@flygoat.com>
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In-Reply-To: <20231028-mm-v1-1-45377cd158cf@flygoat.com>

On Sat, Oct 28, 2023 at 02:52:16PM +0100, Jiaxun Yang wrote:
> SPARSEMEM have been tested on Cavium and Loongson64 for a while
> and we are confident that they are working properly on 64bit
> systems.
> 
> Since it's almost certain for 64bit MIPS system to have a hole
> in memory space, SPARSEMEM will be more efficent for them.
> 
> Also promote platforms marked with SPARSEMEM_ENABLE before
> to SPARSEMEM_DEFAULT, as they tend to have huge holes in
> address space.
> 
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> ---
>  arch/mips/Kconfig             | 13 ++++++++-----
>  arch/mips/loongson2ef/Kconfig |  4 ++--
>  2 files changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 76db82542519..d12e8f3c1d08 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -460,7 +460,7 @@ config MACH_LOONGSON2EF
>  
>  config MACH_LOONGSON64
>  	bool "Loongson 64-bit family of machines"
> -	select ARCH_SPARSEMEM_ENABLE
> +	select ARCH_SPARSEMEM_DEFAULT
>  	select ARCH_MIGHT_HAVE_PC_PARPORT
>  	select ARCH_MIGHT_HAVE_PC_SERIO
>  	select GENERIC_ISA_DMA_SUPPORT_BROKEN
> @@ -656,7 +656,7 @@ config SGI_IP22
>  config SGI_IP27
>  	bool "SGI IP27 (Origin200/2000)"
>  	select ARCH_HAS_PHYS_TO_DMA
> -	select ARCH_SPARSEMEM_ENABLE
> +	select ARCH_SPARSEMEM_DEFAULT
>  	select FW_ARC
>  	select FW_ARC64
>  	select ARC_CMDLINE_ONLY
> @@ -923,7 +923,7 @@ config CAVIUM_OCTEON_SOC
>  	select ZONE_DMA32
>  	select GPIOLIB
>  	select USE_OF
> -	select ARCH_SPARSEMEM_ENABLE
> +	select ARCH_SPARSEMEM_DEFAULT
>  	select SYS_SUPPORTS_SMP
>  	select NR_CPUS_DEFAULT_64
>  	select MIPS_NR_CPU_NR_MAP_1024
> @@ -2573,10 +2573,13 @@ config CPU_SUPPORTS_MSA
>  
>  config ARCH_FLATMEM_ENABLE
>  	def_bool y
> -	depends on !NUMA && !CPU_LOONGSON2EF
>  
>  config ARCH_SPARSEMEM_ENABLE
> -	bool
> +	def_bool y
> +	depends on 64BIT
> +
> +config ARCH_SELECT_MEMORY_MODEL
> +	def_bool ARCH_SPARSEMEM_ENABLE

maybe I'm blind, but I don't see ARCH_SPARSEMEM_DEFAULT declared in
Kconfig for MIPS. So what I'm missing ?

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]