On 03/26/2019 07:24 PM, Mike Rapoport wrote:
> On Tue, Mar 26, 2019 at 01:39:14PM +0530, Anshuman Khandual wrote:
>> 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.
> It's 'LINUXrlz' ;-)
Yeah eventually figured that. Though first 16 patterns switch on/off individual
bits on a given byte, there does not seem to be any order or pattern to it.
Never mind, was just curious.
