linux-kernel - Re: [PATCH v3 08/10] x86: document X86_INTEL

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <8c8a5aa5-f434-4006-b36c-02311b94041f@gmail.com>
Date: Fri, 28 Feb 2025 17:20:54 +0100
From: Ferry Toth <fntoth@...il.com>
To: Arnd Bergmann <arnd@...nel.org>, linux-kernel@...r.kernel.org,
 x86@...nel.org
Cc: Arnd Bergmann <arnd@...db.de>, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Andy Shevchenko <andy@...nel.org>, Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH v3 08/10] x86: document X86_INTEL_MID as 64-bit-only

Hi,

On 26-02-2025 22:37, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
>
> The X86_INTEL_MID code was originally introduced for the 32-bit
> Moorestown/Medfield/Clovertrail platform, later the 64-bit
> Merrifield/Moorefield variants were added, but the final Morganfield
> 14nm platform was canceled before it hit the market.
>
> To help users understand what the option actually refers to, update the
> help text, and add a dependency on 64-bit kernels.
>
> Ferry confirmed that all the hardware can run 64-bit kernels these days,
> but is still testing 32-bit kernels on the Intel Edison board, so this
> remains possible, but is guarded by a CONFIG_EXPERT dependency now,
> to gently push remaining users towards using CONFIG_64BIT.

That is a bit more than I said :-) I only know of Merrifield, as Andy 
removed the SFI bits and got ACPI working. For the other platforms I 
don't know the status. Additionally there are pieces of code where 32b 
runs substantially faster than 64b (I know of at least crc32c).

Maybe Andy can confirm the other platforms?

> Cc: Ferry Toth <fntoth@...il.com>
> Link: https://lore.kernel.org/lkml/d890eecc-97de-4abf-8e0e-b881d5db5c1d@gmail.com/
> Acked-by: Andy Shevchenko <andy@...nel.org>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>   arch/x86/Kconfig | 50 ++++++++++++++++++++++++++++--------------------
>   1 file changed, 29 insertions(+), 21 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index aba32f88870d..42dd3c58abfb 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -548,12 +548,12 @@ config X86_EXTENDED_PLATFORM
>   		RDC R-321x SoC
>   		SGI 320/540 (Visual Workstation)
>   		STA2X11-based (e.g. Northville)
> -		Moorestown MID devices
>   
>   	  64-bit platforms (CONFIG_64BIT=y):
>   		Numascale NumaChip
>   		ScaleMP vSMP
>   		SGI Ultraviolet
> +		Merrifield/Moorefield MID devices
>   
>   	  If you have one of these systems, or if you want to build a
>   	  generic distribution kernel, say Y here - otherwise say N.
> @@ -598,8 +598,31 @@ config X86_UV
>   	  This option is needed in order to support SGI Ultraviolet systems.
>   	  If you don't have one of these, you should say N here.
>   
> -# Following is an alphabetically sorted list of 32 bit extended platforms
> -# Please maintain the alphabetic order if and when there are additions
> +config X86_INTEL_MID
> +	bool "Intel Z34xx/Z35xx MID platform support"
> +	depends on X86_EXTENDED_PLATFORM
> +	depends on X86_PLATFORM_DEVICES
> +	depends on PCI
> +	depends on X86_64 || (EXPERT && PCI_GOANY)
> +	depends on X86_IO_APIC
> +	select I2C
> +	select DW_APB_TIMER
> +	select INTEL_SCU_PCI
> +	help
> +	  Select to build a kernel capable of supporting 64-bit Intel MID
> +	  (Mobile Internet Device) platform systems which do not have
> +	  the PCI legacy interfaces.
> +
> +	  The only supported devices are the 22nm Merrified (Z34xx)
> +	  and Moorefield (Z35xx) SoC used in the Intel Edison board and
> +	  a small number of Android devices such as the Asus Zenfone 2,
> +	  Asus FonePad 8 and Dell Venue 7.
> +
> +	  If you are building for a PC class system or non-MID tablet
> +	  SoCs like Bay Trail (Z36xx/Z37xx), say N here.
> +
> +	  Intel MID platforms are based on an Intel processor and chipset which
> +	  consume less power than most of the x86 derivatives.
>   
>   config X86_GOLDFISH
>   	bool "Goldfish (Virtual Platform)"
> @@ -609,6 +632,9 @@ config X86_GOLDFISH
>   	  for Android development. Unless you are building for the Android
>   	  Goldfish emulator say N here.
>   
> +# Following is an alphabetically sorted list of 32 bit extended platforms
> +# Please maintain the alphabetic order if and when there are additions
> +
>   config X86_INTEL_CE
>   	bool "CE4100 TV platform"
>   	depends on PCI
> @@ -624,24 +650,6 @@ config X86_INTEL_CE
>   	  This option compiles in support for the CE4100 SOC for settop
>   	  boxes and media devices.
>   
> -config X86_INTEL_MID
> -	bool "Intel MID platform support"
> -	depends on X86_EXTENDED_PLATFORM
> -	depends on X86_PLATFORM_DEVICES
> -	depends on PCI
> -	depends on X86_64 || (PCI_GOANY && X86_32)
> -	depends on X86_IO_APIC
> -	select I2C
> -	select DW_APB_TIMER
> -	select INTEL_SCU_PCI
> -	help
> -	  Select to build a kernel capable of supporting Intel MID (Mobile
> -	  Internet Device) platform systems which do not have the PCI legacy
> -	  interfaces. If you are building for a PC class system say N here.
> -
> -	  Intel MID platforms are based on an Intel processor and chipset which
> -	  consume less power than most of the x86 derivatives.
> -
>   config X86_INTEL_QUARK
>   	bool "Intel Quark platform support"
>   	depends on X86_32