linux-kernel - Re: [PATCH v2 6/8] x86: kdump: use generic interface to simplify crashkernel reservation code

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Message-ID: <ZPG4mKmxaU78u/2k@MiWiFi-R3L-srv>
Date:   Fri, 1 Sep 2023 18:10:32 +0800
From:   Baoquan He <bhe@...hat.com>
To:     "Leizhen (ThunderTown)" <thunder.leizhen@...weicloud.com>
Cc:     linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        catalin.marinas@....com, thunder.leizhen@...wei.com,
        dyoung@...hat.com, prudo@...hat.com, samuel.holland@...ive.com,
        kexec@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
        x86@...nel.org
Subject: Re: [PATCH v2 6/8] x86: kdump: use generic interface to simplify
 crashkernel reservation code

On 08/31/23 at 11:43am, Leizhen (ThunderTown) wrote:
......  
> > -static void __init reserve_crashkernel(void)
> > +static void __init arch_reserve_crashkernel(void)
> >  {
> > -	unsigned long long crash_size, crash_base, total_mem;
> > +	unsigned long long crash_base, crash_size, low_size = 0;
> > +	char *cmdline = boot_command_line;
> >  	bool high = false;
> >  	int ret;
> >  
> >  	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
> >  		return;
> >  
> > -	total_mem = memblock_phys_mem_size();
> > -
> > -	/* crashkernel=XM */
> > -	ret = parse_crashkernel(boot_command_line, total_mem,
> > -				&crash_size, &crash_base, NULL, NULL);
> > -	if (ret != 0 || crash_size <= 0) {
> > -		/* crashkernel=X,high */
> > -		ret = parse_crashkernel_high(boot_command_line, total_mem,
> > -					     &crash_size, &crash_base);
> > -		if (ret != 0 || crash_size <= 0)
> > -			return;
> > -		high = true;
> > -	}
> > +	ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
> > +				&crash_size, &crash_base,
> > +				&low_size, &high);
> > +	if (ret)
> > +		return;
> >  
> >  	if (xen_pv_domain()) {
> >  		pr_info("Ignoring crashkernel for a Xen PV domain\n");
> >  		return;
> >  	}
> >  
> > -	/* 0 means: find the address automatically */
> > -	if (!crash_base) {
> > -		/*
> > -		 * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> > -		 * crashkernel=x,high reserves memory over 4G, also allocates
> > -		 * 256M extra low memory for DMA buffers and swiotlb.
> > -		 * But the extra memory is not required for all machines.
> > -		 * So try low memory first and fall back to high memory
> > -		 * unless "crashkernel=size[KMG],high" is specified.
> > -		 */
> > -		if (!high)
> > -			crash_base = memblock_phys_alloc_range(crash_size,
> > -						CRASH_ALIGN, CRASH_ALIGN,
> > -						CRASH_ADDR_LOW_MAX);
> > -		if (!crash_base)
> > -			crash_base = memblock_phys_alloc_range(crash_size,
> > -						CRASH_ALIGN, CRASH_ALIGN,
> > -						CRASH_ADDR_HIGH_MAX);
> > -		if (!crash_base) {
> > -			pr_info("crashkernel reservation failed - No suitable area found.\n");
> > -			return;
> > -		}
> > -	} else {
> > -		unsigned long long start;
> > -
> > -		start = memblock_phys_alloc_range(crash_size, SZ_1M, crash_base,
> > -						  crash_base + crash_size);
> > -		if (start != crash_base) {
> > -			pr_info("crashkernel reservation failed - memory is in use.\n");
> > -			return;
> > -		}
> > -	}
> > -
> > -	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
> > -		memblock_phys_free(crash_base, crash_size);
> > -		return;
> > -	}
> > -
> > -	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
> > -		(unsigned long)(crash_size >> 20),
> > -		(unsigned long)(crash_base >> 20),
> > -		(unsigned long)(total_mem >> 20));
> > +	reserve_crashkernel_generic(cmdline, crash_size, crash_base,
> > +				    low_size, high);
> >  
> > -	crashk_res.start = crash_base;
> > -	crashk_res.end   = crash_base + crash_size - 1;
> > -	insert_resource(&iomem_resource, &crashk_res);
> > +	return;
> 
> This can be omitted.

Will update, thx.

> 
> >  }
......