From: Anshuman Khandual <anshuman.khandual@arm.com>
To: "linux-mm@kvack.org" <linux-mm@kvack.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
Vladimir Murzin <vladimir.murzin@arm.com>,
Tony Luck <tony.luck@intel.com>,
Dan Williams <dan.j.williams@intel.com>
Subject: early_memtest() patterns
Date: Tue, 26 Mar 2019 13:39:14 +0530 [thread overview]
Message-ID: <7da922fb-5254-0d3c-ce2b-13248e37db83@arm.com> (raw)
Hello,
early_memtest() is being executed on many platforms even though they dont enable
CONFIG_MEMTEST by default. Just being curious how the following set of patterns
got decided. Are they just random 64 bit patterns ? Or there is some particular
significance to them in detecting bad memory.
static u64 patterns[] __initdata = {
/* The first entry has to be 0 to leave memtest with zeroed memory */
0,
0xffffffffffffffffULL,
0x5555555555555555ULL,
0xaaaaaaaaaaaaaaaaULL,
0x1111111111111111ULL,
0x2222222222222222ULL,
0x4444444444444444ULL,
0x8888888888888888ULL,
0x3333333333333333ULL,
0x6666666666666666ULL,
0x9999999999999999ULL,
0xccccccccccccccccULL,
0x7777777777777777ULL,
0xbbbbbbbbbbbbbbbbULL,
0xddddddddddddddddULL,
0xeeeeeeeeeeeeeeeeULL,
0x7a6c7258554e494cULL, /* yeah ;-) */
};
BTW what about the last one here. Most of them got moved from x86 through the
commit 63823126c221dd ("x86: memtest: add additional (regular) test patterns").
- Anshuman
next reply other threads:[~2019-03-26 8:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-26 8:09 Anshuman Khandual [this message]
2019-03-26 8:40 ` Michal Hocko
2019-03-26 13:54 ` Mike Rapoport
2019-03-27 11:21 ` Anshuman Khandual
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