Wording improvements, from "Valentin I. Spitkovsky"

[pintos-anon] / doc / vm.texi

diff --git a/doc/vm.texi b/doc/vm.texi
index 3210bbcc83dd021a16f48ad78f7a9284ead20f21..fdbc5c68c492b2900745d29ad6d40cc9ab211080 100644 (file)
--- a/doc/vm.texi
+++ b/doc/vm.texi
@@ -260,7 +260,7 @@ page fault might only indicate that the page must be brought in from a
 file or swap.  You will have to implement a more sophisticated page
 fault handler to handle these cases.  Your page fault handler, which you
 should implement by modifying @func{page_fault} in
-@file{threads/exception.c}, needs to do roughly the following:
+@file{userprog/exception.c}, needs to do roughly the following:
 
 @enumerate 1
 @item
@@ -576,7 +576,7 @@ bytes below the stack pointer.
 
 You will need to be able to obtain the current value of the user
 program's stack pointer.  Within a system call or a page fault generated
-by a user program, you can retrieve it from @code{esp} member of the
+by a user program, you can retrieve it from the @code{esp} member of the
 @struct{intr_frame} passed to @func{syscall_handler} or
 @func{page_fault}, respectively.  If you verify user pointers before
 accessing them (@pxref{Accessing User Memory}), these are the only cases
@@ -590,16 +590,14 @@ user stack pointer.  You will need to arrange another way, such as
 saving @code{esp} into @struct{thread} on the initial transition 
 from user to kernel mode.
 
-You may impose some absolute limit on stack size, as do most OSes.
+You should impose some absolute limit on stack size, as do most OSes.
 Some OSes make the limit user-adjustable, e.g.@: with the
 @command{ulimit} command on many Unix systems.  On many GNU/Linux systems,
 the default limit is 8 MB.
 
-The first stack page need not be allocated lazily.  You can initialize
-it with the command line arguments at load time, with no need to wait
-for it to be faulted in.  (Even if you did wait, the very first
-instruction in the user program is likely to be one that faults in the
-page.)
+The first stack page need not be allocated lazily.  You can allocate
+and initialize it with the command line arguments at load time, with 
+no need to wait for it to be faulted in.
 
 All stack pages should be candidates for eviction.  An evicted stack
 page should be written to swap.
@@ -615,7 +613,7 @@ space.  The entire file is mapped into consecutive virtual pages
 starting at @var{addr}.
 
 Your VM system must lazily load pages in @code{mmap} regions and use the
-@code{mmap}'d file itself as backing store for the mapping.  That is,
+@code{mmap}ed file itself as backing store for the mapping.  That is,
 evicting a page mapped by @code{mmap} writes it back to the file it was
 mapped from.
 
@@ -716,6 +714,12 @@ process.  If you carefully designed your data structures,
 sharing of read-only pages should not make this part significantly
 harder.
 
+@item How do we resume a process after we have handled a page fault?
+
+Returning from @func{page_fault} resumes the current user process
+(@pxref{Internal Interrupt Handling}).
+It will then retry the instruction to which the instruction pointer points.
+
 @item Does the virtual memory system need to support data segment growth?
 
 No.  The size of the data segment is determined by the linker.  We still