linux-kernel - Re: [PATCH v17 03/10] x86: kdump: use macro CRASH_ADDR_LOW_MAX in functions reserve

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Date:   Thu, 16 Dec 2021 09:10:40 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Zhen Lei <thunder.leizhen@...wei.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        Dave Young <dyoung@...hat.com>,
        Vivek Goyal <vgoyal@...hat.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        kexec@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org, Jonathan Corbet <corbet@....net>,
        linux-doc@...r.kernel.org, Randy Dunlap <rdunlap@...radead.org>,
        Feng Zhou <zhoufeng.zf@...edance.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Chen Zhou <dingguo.cz@...group.com>
Subject: Re: [PATCH v17 03/10] x86: kdump: use macro CRASH_ADDR_LOW_MAX in
 functions reserve_crashkernel()

On 12/15/21 at 02:28pm, Borislav Petkov wrote:
> On Fri, Dec 10, 2021 at 02:55:26PM +0800, Zhen Lei wrote:
> > @@ -518,7 +519,7 @@ static void __init reserve_crashkernel(void)
> >  		}
> >  	}
> >  
> > -	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
> > +	if (crash_base >= CRASH_ADDR_LOW_MAX && reserve_crashkernel_low()) {
> >  		memblock_phys_free(crash_base, crash_size);
> >  		return;
> >  	}
> 
> That's not a equivalent transformation on X86_32.

reserve_crashkernel_low() always return 0 on x86_32, so the not equivalent
transformation for x86_32 doesn't matter, I think.