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

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Message-ID: <CAMuHMdXt=UH_YoiRDRHCiHBCAsyyHenz2bDKkqUxF85tj2y6mw@mail.gmail.com>
Date:	Mon, 16 Nov 2015 14:05:55 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Greg Ungerer <gerg@...inux.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 Greg,

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

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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