Why is AHCI built-in?

poma pomidorabelisima at gmail.com
Wed Aug 28 23:57:19 UTC 2013


On 28.08.2013 16:57, Kyle McMartin wrote:
> On Wed, Aug 28, 2013 at 12:46:31AM +0200, poma wrote:
>> Any links/docs to offer on this topic?
>> Thanks.
>>
> 
> I don't have a link off-hand, but a book about computer architecture
> should let you figure things out:
> 
> At what level of detail? The kernel attempts to map itself using
> 2MB pages on X86 where possible (since it's large and contiguous.)
> 
> For various reasons, modules are mapped using 4K pages since they'd need
> to be padded out to 2MB (very little module .text would be that big, and
> obviously code and data are mapped separately for protection reasons.)
> Also, separate modules need to be on separate pages in order to ensure
> that you can remove them independently.
> 
> So the more modules you have loaded, the more likely useful TLB
> (translation lookaside buffer, which caches virtual to physical
> mappings) from userspace will get pushed out by the kernel on a system
> call or interrupt.
> 
> regards, Kyle
> 

This is a good starting point. Thank you.


poma




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