[PATCH 5/5] kexec: X86: Pass memory ranges via e820 table instead of memmap= boot parameter

HATAYAMA Daisuke d.hatayama at jp.fujitsu.com
Mon Apr 15 03:58:08 EDT 2013

(2013/04/15 14:58), Dave Hansen wrote:
> On 04/14/2013 09:52 PM, HATAYAMA Daisuke wrote:
>> This sounds like there's no such issue on x86 cache mechanism. Is it
>> correct? If so, what is the difference between ia64 and x86 cache
>> mechanisms?
> I'm just going by the code comments:
> drivers/char/mem.c
>>                  /*
>>                   * On ia64 if a page has been mapped somewhere as uncached, then
>>                   * it must also be accessed uncached by the kernel or data
>>                   * corruption may occur.
>>                   */

I think it reasonable, in complexity of design, to decide cache or 
uncache according to whether target memory is RAM or some device. If 
we're concerned about page levels, things are to be complicated further 
since memory typing is done per pages. How large does such table become 
to represent memory types for all the target pages, how do we create it 
and when? (I don't know ia64 but I guess caching on ia64 is also done in 
per pages just like x86...)


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