linux-kernel - [PATCH 08/11] x86: document X86_INTEL

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Message-Id: <20241204103042.1904639-9-arnd@kernel.org>
Date: Wed,  4 Dec 2024 11:30:39 +0100
From: Arnd Bergmann <arnd@...nel.org>
To: 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>,
	Sean Christopherson <seanjc@...gle.com>,
	Davide Ciminaghi <ciminaghi@...dd.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	kvm@...r.kernel.org
Subject: [PATCH 08/11] x86: document X86_INTEL_MID as 64-bit-only

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 variant got added, but the final
Morganfield/Broxton 14nm chips were canceled before they hit
the market.

To help users understand what the option actually refers to,
update the help text, and make it a hard dependency on 64-bit
kernels. While they could theoretically run a 32-bit kernel,
the devices originally shipped with 64-bit one in 2015, so that
was proabably never tested.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/x86/Kconfig         | 16 ++++++++++------
 arch/x86/kernel/head32.c |  3 ---
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d8a8bf9ea9b9..fa6dd9ec4bdf 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -544,12 +544,12 @@ 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.
@@ -621,11 +621,11 @@ config X86_INTEL_CE
 	  boxes and media devices.
 
 config X86_INTEL_MID
-	bool "Intel MID platform support"
+	bool "Intel Z34xx/Z35xx 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_64
 	depends on X86_IO_APIC
 	select I2C
 	select DW_APB_TIMER
@@ -633,10 +633,14 @@ config X86_INTEL_MID
 	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.
+	  interfaces.
+
+	  The only supported devices are the 22nm Merrified (Z34xx) and
+	  Moorefield (Z35xx) SoC used in Android devices such as the
+	  Asus Zenfone 2, Asus FonePad 8 and Dell Venue 7.
 
-	  Intel MID platforms are based on an Intel processor and chipset which
-	  consume less power than most of the x86 derivatives.
+	  If you are building for a PC class system or non-MID tablet
+	  SoCs like Bay Trail (Z36xx/Z37xx), say N here.
 
 config X86_INTEL_QUARK
 	bool "Intel Quark platform support"
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index de001b2146ab..4f69239556e4 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -65,9 +65,6 @@ asmlinkage __visible void __init __noreturn i386_start_kernel(void)
 
 	/* Call the subarch specific early setup function */
 	switch (boot_params.hdr.hardware_subarch) {
-	case X86_SUBARCH_INTEL_MID:
-		x86_intel_mid_early_setup();
-		break;
 	case X86_SUBARCH_CE4100:
 		x86_ce4100_early_setup();
 		break;
-- 
2.39.5