linux-kernel - Re: [PATCH 20/29] x86/boot/e820: Clean up e820__setup_pci_gap()/e820_search

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Message-ID: <aCXTm-BH2QopFIGV@gmail.com>
Date: Thu, 15 May 2025 13:44:27 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Andy Shevchenko <andy@...nel.org>
Cc: linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...nel.org>,
	Borislav Petkov <bp@...en8.de>, Juergen Gross <jgross@...e.com>,
	"H . Peter Anvin" <hpa@...or.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>,
	Thomas Gleixner <tglx@...utronix.de>,
	David Woodhouse <dwmw@...zon.co.uk>
Subject: Re: [PATCH 20/29] x86/boot/e820: Clean up
 e820__setup_pci_gap()/e820_search_gap() a bit


* Andy Shevchenko <andy@...nel.org> wrote:

> On Mon, Apr 21, 2025 at 08:52:00PM +0200, Ingo Molnar wrote:
> > Use a bit more readable variable names, we haven't run out of
> > underscore characters in the kernel yet.
> 
> Size notes:
> 
> > +	gap_size = 0x400000;
> 
> SZ_4M ?
> 
> ...
> 
> > +		gap_start = (max_pfn << PAGE_SHIFT) + 1024*1024;
> 
> SZ_1M ?

Good point - delta patch below folded back & propagated to the rest of 
the series.

Thanks,

	Ingo

===============================>
 arch/x86/kernel/e820.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 3baf558107e7..d00ca2dd20b7 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -722,12 +722,12 @@ __init void e820__setup_pci_gap(void)
 	unsigned long gap_start, gap_size;
 	int found;
 
-	gap_size = 0x400000;
+	gap_size = SZ_4M;
 	found  = e820_search_gap(&gap_start, &gap_size);
 
 	if (!found) {
 #ifdef CONFIG_X86_64
-		gap_start = (max_pfn << PAGE_SHIFT) + 1024*1024;
+		gap_start = (max_pfn << PAGE_SHIFT) + SZ_1M;
 		pr_err("Cannot find an available gap in the 32-bit address range\n");
 		pr_err("PCI devices with unassigned 32-bit BARs may not work!\n");
 #else