X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Fvm.texi;h=e6ff141067f58ce2b80cbb2f2a807a018267519d;hb=13753f29344700c01d9dc80834e51c7303ed18f7;hp=6e5d5a076b281bdb6dd72515e9b2c22b792fbf93;hpb=b0498d0f3428dfd14e7b679990f0a4a605a1287e;p=pintos-anon

diff --git a/doc/vm.texi b/doc/vm.texi
index 6e5d5a0..e6ff141 100644
--- a/doc/vm.texi
+++ b/doc/vm.texi
@@ -316,11 +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}).
 
-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
-in @bibref{IA32-v3}, 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
@@ -419,11 +420,10 @@ Bits}) to implement an approximation to LRU.  Your algorithm should
 perform at least as well as the ``second chance'' or ``clock''
 algorithm.
 
-Your design should allow for parallelism.  Multiple processes should
-be able to process page faults at once.  If one page fault require
+Your design should allow for parallelism.  If one page fault requires
 I/O, in the meantime processes that do not fault should continue
-executing and other page faults that do not require I/O should be able to
-complete.  These criteria require some synchronization effort.
+executing and other page faults that do not require I/O should be able
+to complete.  These criteria require some synchronization effort.
 
 @node Lazy Loading
 @subsection Lazy Loading
@@ -440,25 +440,25 @@ be written to swap.
 
 The core of the program loader is the loop in @func{load_segment} in
 @file{userprog/process.c}.
-Each time around the loop, @code{read_bytes} receives the number of
-bytes to read from the executable file and @code{zero_bytes} receives
+Each time around the loop, @code{page_read_bytes} receives the number of
+bytes to read from the executable file and @code{page_zero_bytes} receives
 the number of bytes to initialize to zero following the bytes read.  The
 two always sum to @code{PGSIZE} (4,096).  The handling of a page depends
 on these variables' values:
 
 @itemize @bullet
 @item
-If @code{read_bytes} equals @code{PGSIZE}, the page should be demand
+If @code{page_read_bytes} equals @code{PGSIZE}, the page should be demand
 paged from disk on its first access.
 
 @item
-If @code{zero_bytes} equals @code{PGSIZE}, the page does not need to
+If @code{page_zero_bytes} equals @code{PGSIZE}, the page does not need to
 be read from disk at all because it is all zeroes.  You should handle
 such pages by creating a new page consisting of all zeroes at the
 first page fault.
 
 @item
-If neither @code{read_bytes} nor @code{zero_bytes} equals
+If neither @code{page_read_bytes} nor @code{page_zero_bytes} equals
 @code{PGSIZE}, then part of the page is to be read from disk and the
 remainder zeroed.  This is a special case.  You are allowed to handle
 it by reading the partial page from disk at executable load time and
@@ -669,7 +669,7 @@ 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.
 
-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.
 
@@ -712,7 +712,7 @@ with the file mapped into your address space, you can directly address
 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,