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Diffstat (limited to 'microkernel/mach/pmap.mdwn')
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diff --git a/microkernel/mach/pmap.mdwn b/microkernel/mach/pmap.mdwn new file mode 100644 index 00000000..6910bfd3 --- /dev/null +++ b/microkernel/mach/pmap.mdwn @@ -0,0 +1,74 @@ +[[!meta copyright="Copyright © 2012 Free Software Foundation, Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +[[!tag open_issue_documentation open_issue_gnumach]] + + +# IRC, freenode, #hurd, 2012-02-01 + + <sekon> on Hurd what is the difference between kernel memory object and + pmap module ?? + <sekon> pmap is heap/libraries table for each thread while kernel memory + object refers to arbitary blobs of data ?? + <braunr> sekon: pmap is the low level memory mapping module + <braunr> i.e. it programs the mmu + <braunr> and these aren't hurd-specific, they are mach modules + <sekon> braunr: so kernel memonry objects consists of a bunch of pmaps ?? + <braunr> sekon: memory objects can be various things, be specific please + <braunr> (they're certainly not a bunch of pmaps though, no) + <braunr> there is one pmap per vm_map, and there is one vm_map per task + <braunr> and there is no need for double question marks, is ther ?? + <sekon> lol then is kernel memory object , please excuse the metaphor + something like a base class for pmap + <braunr> i don't know what a "kernel memory object" is, be specific please, + again + <sekon> braunr: + http://courses.cs.vt.edu/~cs5204/fall05-gback/presentations/MachOS_Rajesh.ppt + <sekon> goto page titled External Memory Management (EMM) on page 15 + <sekon> Kernel memory object shows up + <braunr> you know there are other formats for this document + <sekon> nope .. i did not know that + <sekon> in page 17 pmamp shows up + <braunr> "the problems of external memory management" ? + <sekon> braunr: the paper i am also reading is called x15mach_thesis + <braunr> ah, that's mine + * sekon bows + <sekon> :) + <braunr> ok i see page 17 + <sekon> so please good sir explain the relationship between kernel memory + object and pmap + <sekon> (if any) + <sekon> braunr: there is no mention of kernel memory object + <braunr> again, i don't see any reference or definition of "kernel memory + object" + <sekon> but your paper says + <sekon> that when page faults occur + <sekon> the kernel contact the manager for a kernel reference object + <sekon> *memory + <braunr> where ? + <sekon> in section 2.1.3 (unless i read it wrong) + <sekon> no just a sec + <sekon> 2.1.5 + <braunr> i never used the expression "kernel memory object" there :p + <braunr> anyway, you're referring simple to memory objects as seen by + userspace pagers + <braunr> a memory object is a data container + <braunr> usually, it's a file + <braunr> but it can be anything + <braunr> the pager is the task that provides its content and implements the + object methods + <braunr> as for the relation between them and the pmap module, it's a + distant one + <braunr> i'll explain it with an example + <braunr> page fault -> request content of memory object at a given offset + with given length from pager -> ask pmap to establish the mapping in the + mmu + <sekon> braunr: thank you ver much + <sekon> *very |