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Message-ID: <20191205091311.GD2810@hirez.programming.kicks-ass.net>
Date: Thu, 5 Dec 2019 10:13:11 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Wei Yang <richardw.yang@...ux.intel.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
richard.weiyang@...il.com, dave.hansen@...ux.intel.com,
luto@...nel.org, peterz@...radead.or, tglx@...utronix.de
Subject: Re: [Patch v2 4/6] x86/mm: Refine debug print string retrieval
function
On Thu, Dec 05, 2019 at 10:14:01AM +0800, Wei Yang wrote:
> Generally, the mapping page size are:
>
> 4K, 2M, 1G
>
> except in case 32-bit without PAE, the mapping page size are:
>
> 4K, 4M
>
> Based on PG_LEVEL_X definition and mr->page_size_mask, we can calculate
> the mapping page size from a predefined string array.
>
> Signed-off-by: Wei Yang <richardw.yang@...ux.intel.com>
> ---
> arch/x86/mm/init.c | 39 +++++++++++++--------------------------
> 1 file changed, 13 insertions(+), 26 deletions(-)
>
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index 0eb5edb63fa2..ded58a31c679 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -308,29 +308,20 @@ static void __ref adjust_range_page_size_mask(struct map_range *mr,
> }
> }
>
> +static void __meminit mr_print(struct map_range *mr, unsigned int maxidx)
> {
> +#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
> + static const char *sz[2] = { "4K", "4M" };
> +#else
> + static const char *sz[4] = { "4K", "2M", "1G", "" };
> +#endif
> + unsigned int idx, s;
>
> + for (idx = 0; idx < maxidx; idx++, mr++) {
> + s = (mr->page_size_mask >> PG_LEVEL_2M) & (ARRAY_SIZE(sz) - 1);
Is it at all possible for !PAE to have 1G here, if you use the sz[4]
definition unconditionally?
> + pr_debug(" [mem %#010lx-%#010lx] page size %s\n",
> + mr->start, mr->end - 1, sz[s]);
> + }
> }
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