Studying ‘mmap()/munmap()’Experiment #1Details of our Plan #1Experiment #2Details of our Plan #2What to turn in today?Studying ‘mmap()/munmap()’ How we can use our ‘toolbox’ of kernel modules to examine the effects of ‘mmap()/munmap()’Experiment #1•Remember our ‘vma.c’ module?•It creates a ‘/proc’ file•It shows a task’s virtual memory areas•NOTE: It works only for the ‘current’ task•We do BEFORE and AFTER comparisonsDetails of our Plan #1•Install the ‘vma.c’ module•Install ‘mysis.c’ device-driver•Write an application: ‘mmstudy1.cpp’–Open the files ‘/dev/mysis’ and ‘/proc/vma’–Read and display contents of ‘/proc/vma’ –Call ‘mmap()’ to map the video frame-buffer–Read and display contents of ‘/proc/vma’ –Call ‘munmap()’ to unmap the frame-buffer–Read and display contents of ‘/proc/vma’Experiment #2•We want to examine a task’s page-tables•We need to use our ‘ram.c’ device-driver•We also need a new ‘/proc’ file: ‘cr3.c’•CR3 = physical address of page-directory •Page-Directory = page-table addresses•We again do BEFORE and AFTER looksDetails of our Plan #2•Install modules ‘cr3.c’ and ‘ram.c’•Write an application: ‘mmstudy2.cpp’–Open: /proc/cr3, ‘/dev/ram’ and ‘/dev/vram’–Read page-directory and page-table(s)–Call ‘mmap()’ to map the video frame-buffer–Read page-directory and page-table(s)–Call ‘munmap()’ to unmap the frame-buffer–Read page-directory and page-table(s)–Compare tables (to see if anything changed)What to turn in today?•Turn in a printout of your source-code: –for ‘mmstudy1.cpp’ and for ‘mmstudy2.cpp’•Turn in a printout of your program output: –from ‘mmstudy1’ and from ‘mmstudy2’•You may ask for assistance –from Instructor, from TA, from
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