[GTALUG] python sweetness — The mysterious case of the Linux Page Table

[David Collier-Brown]

On 04/01/18 11:22 AM, Lennart Sorensen via talk wrote:
> On Thu, Jan 04, 2018 at 12:54:50AM -0500, Russell via talk wrote:
>> For a problem like this one and given it's scope and complexity, it is premature to downplay the core and it's overhead issue. This is not like in the movies where the producer says, it's not a problem, we can fix it in POST. This is a preproduction issue with the actors.
>>
>> If you want to get all biological about pathology. The pathology of this problem is far from well understood. Finding the proper namespace is important.
>>
>> At Linus's request KAISER has been dropped. However fuckwit (Forcefully Unmap Complete Kernel With Interrupt Trampolines, ) has not been adopted, by most people anyway.
>>
>> https://lkml.org/lkml/2017/12/4/709
> Well code I see committed in the kernel uses pti_ for the functions,
> so seems they settled on page table isolation.  It was previously
> suggesting kpti for kernel page table isolation but I guess the kernel
> bit was deemed redundant.
>
 From what I read, it was the time cost of going between subset and 
superset of page tables on every systems call or interrupt that caused 
push-back. There was also some discussion of deferring the change until 
there was a better algorithm, but it looks like the Intel issue came 
along and "motivated" more rapid action.

/When a man knows he is to be hanged in a fortnight, it concentrates his 
mind wonderfully. /-- Samuel Johnson

--dave

-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb at spamcop.net           |                      -- Mark Twain

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