linux-kernel - Re: [PATCH v18 15/17] of: fdt: Aggregate the processing of "linux,usable-memory-range"

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Message-ID: <e9f66aca-f399-bf79-3e01-91d419442788@oracle.com>
Date:   Thu, 23 Dec 2021 09:48:18 -0600
From:   Dave Kleikamp <dave.kleikamp@...cle.com>
To:     Zhen Lei <thunder.leizhen@...wei.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H . Peter Anvin" <hpa@...or.com>,
        linux-kernel@...r.kernel.org, Dave Young <dyoung@...hat.com>,
        Baoquan He <bhe@...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
Cc:     Randy Dunlap <rdunlap@...radead.org>,
        Feng Zhou <zhoufeng.zf@...edance.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Chen Zhou <dingguo.cz@...group.com>,
        John Donnelly <John.p.donnelly@...cle.com>,
        Pingfan Liu <kernelfans@...il.com>
Subject: Re: [PATCH v18 15/17] of: fdt: Aggregate the processing of
 "linux,usable-memory-range"

On 12/22/21 7:08AM, Zhen Lei wrote:
> Currently, we parse the "linux,usable-memory-range" property in
> early_init_dt_scan_chosen(), to obtain the specified memory range of the
> crash kernel. We then reserve the required memory after
> early_init_dt_scan_memory() has identified all available physical memory.
> Because the two pieces of code are separated far, the readability and
> maintainability are reduced. So bring them together.

Rob Herring is pushing a modified version of this patch (changes made by
Pingfan Liu) to fix a regression. This will cause a conflict when it hits
mainline.

https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/log/?h=dt/linus

https://lore.kernel.org/linux-arm-kernel/20211214040157.27443-1-kernelfans@gmail.com/

> 
> Suggested-by: Rob Herring <robh@...nel.org>
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> Reviewed-by: Rob Herring <robh@...nel.org>
> Tested-by: Dave Kleikamp <dave.kleikamp@...cle.com>
> ---
>   drivers/of/fdt.c | 15 +++++++++++----
>   1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index bdca35284cebd56..37b477a51175359 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -965,8 +965,7 @@ static void __init early_init_dt_check_for_elfcorehdr(unsigned long node)
>   		 elfcorehdr_addr, elfcorehdr_size);
>   }
>   
> -static phys_addr_t cap_mem_addr;
> -static phys_addr_t cap_mem_size;
> +static unsigned long chosen_node_offset = -FDT_ERR_NOTFOUND;
>   
>   /**
>    * early_init_dt_check_for_usable_mem_range - Decode usable memory range
> @@ -977,6 +976,11 @@ static void __init early_init_dt_check_for_usable_mem_range(unsigned long node)
>   {
>   	const __be32 *prop;
>   	int len;
> +	phys_addr_t cap_mem_addr;
> +	phys_addr_t cap_mem_size;
> +
> +	if ((long)node < 0)
> +		return;
>   
>   	pr_debug("Looking for usable-memory-range property... ");
>   
> @@ -989,6 +993,8 @@ static void __init early_init_dt_check_for_usable_mem_range(unsigned long node)
>   
>   	pr_debug("cap_mem_start=%pa cap_mem_size=%pa\n", &cap_mem_addr,
>   		 &cap_mem_size);
> +
> +	memblock_cap_memory_range(cap_mem_addr, cap_mem_size);
>   }
>   
>   #ifdef CONFIG_SERIAL_EARLYCON
> @@ -1137,9 +1143,10 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>   	    (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
>   		return 0;
>   
> +	chosen_node_offset = node;
> +
>   	early_init_dt_check_for_initrd(node);
>   	early_init_dt_check_for_elfcorehdr(node);
> -	early_init_dt_check_for_usable_mem_range(node);
>   
>   	/* Retrieve command line */
>   	p = of_get_flat_dt_prop(node, "bootargs", &l);
> @@ -1275,7 +1282,7 @@ void __init early_init_dt_scan_nodes(void)
>   	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
>   
>   	/* Handle linux,usable-memory-range property */
> -	memblock_cap_memory_range(cap_mem_addr, cap_mem_size);
> +	early_init_dt_check_for_usable_mem_range(chosen_node_offset);
>   }
>   
>   bool __init early_init_dt_scan(void *params)