linux-kernel - [tip: x86/boot] x86/boot/e820: Simplify the PPro Erratum #50 workaround

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Message-ID: <176570146639.498.17304505535216995399.tip-bot2@tip-bot2>
Date: Sun, 14 Dec 2025 08:37:46 -0000
From: "tip-bot2 for Ingo Molnar" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Ingo Molnar <mingo@...nel.org>, "H . Peter Anvin" <hpa@...or.com>,
 Andy Shevchenko <andy@...nel.org>, Arnd Bergmann <arnd@...nel.org>,
 David Woodhouse <dwmw@...zon.co.uk>, Juergen Gross <jgross@...e.com>,
 Kees Cook <keescook@...omium.org>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Mike Rapoport <rppt@...nel.org>, Paul Menzel <pmenzel@...gen.mpg.de>,
 Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject:
 [tip: x86/boot] x86/boot/e820: Simplify the PPro Erratum #50 workaround

The following commit has been merged into the x86/boot branch of tip:

Commit-ID:     3814bf08452ecfc6db0de53a2e4f977e9661c1f4
Gitweb:        https://git.kernel.org/tip/3814bf08452ecfc6db0de53a2e4f977e9661c1f4
Author:        Ingo Molnar <mingo@...nel.org>
AuthorDate:    Thu, 15 May 2025 14:05:19 +02:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Sun, 14 Dec 2025 09:19:37 +01:00

x86/boot/e820: Simplify the PPro Erratum #50 workaround

No need to print out the table - users won't really be able
to tell much from it anyway and the messages around this
erratum are unnecessarily obtuse.

Instead clearly inform the user that a 256 kB hole is being
punched in their memory map at the 1.75 GB physical address.

Not that there are many PPro users left. :-)

Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: H . Peter Anvin <hpa@...or.com>
Cc: Andy Shevchenko <andy@...nel.org>
Cc: Arnd Bergmann <arnd@...nel.org>
Cc: David Woodhouse <dwmw@...zon.co.uk>
Cc: Juergen Gross <jgross@...e.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Rapoport <rppt@...nel.org>
Cc: Paul Menzel <pmenzel@...gen.mpg.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Link: https://patch.msgid.link/20250515120549.2820541-4-mingo@kernel.org
---
 arch/x86/kernel/setup.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 1b2edd0..a231b24 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1015,11 +1015,9 @@ void __init setup_arch(char **cmdline_p)
 	trim_bios_range();
 #ifdef CONFIG_X86_32
 	if (ppro_with_ram_bug()) {
-		e820__range_update(0x70000000ULL, 0x40000ULL, E820_TYPE_RAM,
-				  E820_TYPE_RESERVED);
+		pr_info("Applying PPro RAM bug workaround: punching 256 kB hole at 1.75 GB physical.\n");
+		e820__range_update(0x70000000ULL, SZ_256K, E820_TYPE_RAM, E820_TYPE_RESERVED);
 		e820__update_table(e820_table);
-		printk(KERN_INFO "fixed physical RAM map:\n");
-		e820__print_table("bad_ppro");
 	}
 #else
 	early_gart_iommu_check();