add structs into proj2 and some simple explanations

1 files changed, 16 insertions, 0 deletions

diff --git a/proj2.txt b/proj2.txt
index 8dd36f2..8572b3f 100644
--- a/proj2.txt
+++ b/proj2.txt
@@ -104,6 +104,17 @@ an exception.
 >> `struct' member, global or static variable, `typedef', or
 >> enumeration.  Identify the purpose of each in 25 words or less.
 
+struct mmap_table:
+  struct mmap_table_entry **ids;
+  int id_free;            ...lowest-index free
+  int id_max;             ...highest-index used
+  int id_cap;             ...mmap table capacity
+
+struct mmap_table_entry:
+  void *upage;            ...virtual address of first page of mmapped file
+  struct file *file;      ...file handle
+  int pages;              ...number of pages the mapping needs
+
 struct page_table_entry:
   union struct TODO       ...structure needed for loading of memory mapped files
 
@@ -112,11 +123,15 @@ struct page_table_entry:
 >> C2: Describe how memory mapped files integrate into your virtual
 >> memory subsystem.
 
+for every page required by the memory mapped file we create a new page table
+entry
 TODO
 
 >> C3: Explain how you determine whether a new file mapping overlaps
 >> any existing segment.
 
+in mmap() we simply check if the required pages are still free (no entry in
+the page table).
 TODO
 
 ---- RATIONALE ----
@@ -128,6 +143,7 @@ TODO
 >> implementation either does or does not share much of the code for
 >> the two situations.
 
+we share the same page table entries
 TODO
 
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