linux-kernel - Re: [PATCH 4/4] m68knommu: Add missing initialization of max_pfn and {min,max}_low

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Date:	Tue, 17 Nov 2015 09:46:33 +1000
From:	Greg Ungerer <gerg@...inux.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Sam Creasey <sammy@...my.net>,
	linux-m68k <linux-m68k@...ts.linux-m68k.org>,
	Linux-Arch <linux-arch@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] m68knommu: Add missing initialization of max_pfn and
 {min,max}_low_pfn

Hi Geert,

On 16/11/15 23:05, Geert Uytterhoeven wrote:
> On Mon, Nov 16, 2015 at 1:18 PM, Greg Ungerer <gerg@...inux.org> wrote:
>>> --- a/arch/m68k/kernel/setup_no.c
>>> +++ b/arch/m68k/kernel/setup_no.c
>>> @@ -238,11 +238,14 @@ void __init setup_arch(char **cmdline_p)
>>>          * Give all the memory to the bootmap allocator, tell it to put
>>> the
>>>          * boot mem_map at the start of memory.
>>>          */
>>> +       min_low_pfn = PFN_DOWN(memory_start);
>>> +       max_pfn = max_low_pfn = PFN_DOWN(memory_end);
>>> +
>>>         bootmap_size = init_bootmem_node(
>>>                         NODE_DATA(0),
>>> -                       memory_start >> PAGE_SHIFT, /* map goes here */
>>> -                       PAGE_OFFSET >> PAGE_SHIFT,      /* 0 on coldfire
>>> */
>>> -                       memory_end >> PAGE_SHIFT);
>>> +                       min_low_pfn,            /* map goes here */
>>> +                       PFN_DOWN(PAGE_OFFSET),  /* 0 on coldfire */
>>> +                       max_pfn);
>>>         /*
>>>          * Free the usable memory, we have to make sure we do not free
>>>          * the bootmem bitmap so we then reserve it after freeing it :-)
>>
>> Should this be changed to use init_bootmem() as per your changes
>> in patch 3 ("m68k/mm: sun3 - Add missing initialization of max_pfn and
>> {min,max}_low_pfn")? For the same reason?
> 
> No. PAGE_OFFSET = PAGE_OFFSET_RAW = CONFIG_RAMBASE.
> As the comment says, this is zero on coldfire, but not on all m68knommu
> platforms.
> 
> Upon closer look, this isn't even true on all Coldfire boards:
> 
> arch/m68k/configs/m5208evb_defconfig:CONFIG_RAMBASE=0x40000000

Yes, that comment is definitely wrong!

Regards
Greg


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