Clarify comment.

[pintos-anon] / doc / vm.texi

diff --git a/doc/vm.texi b/doc/vm.texi
index 840e506a129586d9c2857f22a86a4325cdfafc01..3703a94a5a301c147d55629007d69b6dfa746591 100644 (file)
--- a/doc/vm.texi
+++ b/doc/vm.texi
@@ -316,12 +316,12 @@ Some way of translating in software from virtual page frames to
 physical page frames.  Pintos provides a hash table that you may find
 useful for this purpose (@pxref{Hash Table}).
 
 physical page frames.  Pintos provides a hash table that you may find
 useful for this purpose (@pxref{Hash Table}).
 

-It is possible to do this translation without adding a new data
-structure, by modifying the code in @file{userprog/pagedir.c}.  However,
-if you do that you'll need to carefully study and understand section
-3.7, ``Page Translation Using 32-Bit Physical Addressing,'' in
-@bibref{IA32-v3a}, and in practice it is probably easier to add a new
-data structure.
+You don't strictly need a new data structure for this.  You could
+instead modify the code in @file{userprog/pagedir.c}.  If you do that
+you'll need to thoroughly understand how 80@var{x}86 page tables work
+by, e.g.,@: studying section 3.7, ``Page Translation Using 32-Bit
+Physical Addressing,'' in @bibref{IA32-v3a}.  In practice, most groups
+use a separate data structure.

 
 @item
 Some way of finding a page on disk (in a file or in swap) if it is not
 
 @item
 Some way of finding a page on disk (in a file or in swap) if it is not


@@ -670,7 +670,7 @@ kernel functions need to obtain memory.
 You can layer some other allocator on top of @func{palloc_get_page} if
 you like, but it should be the underlying mechanism.
 
 You can layer some other allocator on top of @func{palloc_get_page} if
 you like, but it should be the underlying mechanism.
 

-Also, you can use the @option{-u} option to @command{pintos} to limit
+Also, you can use the @option{-ul} option to @command{pintos} to limit

 the size of the user pool, which makes it easy to test your VM
 implementation with various user memory sizes.
 
 the size of the user pool, which makes it easy to test your VM
 implementation with various user memory sizes.
 


@@ -713,7 +713,7 @@ with the file mapped into your address space, you can directly address
 it like so:
 
 @example
 it like so:
 
 @example

-write (addr, 64, STDOUT_FILENO);
+write (STDOUT_FILENO, addr, 64);

 @end example
 
 Similarly, if you wanted to replace the first byte of the file,
 @end example
 
 Similarly, if you wanted to replace the first byte of the file,