diff --git a/input/chapter01/chapter01.xml b/input/chapter01/chapter01.xml index 252a2cdb..ba8f169a 100644 --- a/input/chapter01/chapter01.xml +++ b/input/chapter01/chapter01.xml @@ -411,7 +411,7 @@ kilo binary byte (shortened to KiB). The other prefixes have a similar prefix (Mebibyte, MiB, for example). Tradition largely prevents use of these terms, - but you may seem them in some literature. + but you may see them in some literature.
@@ -1766,7 +1766,7 @@ 2^8 = 256 possible values; with our sign bit representation we could represent -127 thru 127 but with - two's complement we can represent -127 thru 128. This is + two's complement we can represent -128 thru 127. This is because we have removed the problem of having two zeros; consider that "negative zero" is (~00000000 +1)=(11111111+1)=00000000 (note diff --git a/input/chapter02/chapter02.xml b/input/chapter02/chapter02.xml index ded47365..2c260986 100644 --- a/input/chapter02/chapter02.xml +++ b/input/chapter02/chapter02.xml @@ -519,7 +519,7 @@ instructions also allows for alternate implementations which may take advantage of the nature of instruction streaming; they are read-only so do not need expensive on-chip features - such as multi-porting, nor need to handle handle sub-block + such as multi-porting, nor need to handle sub-block reads because the instruction stream generally uses more regular sized accesses.
@@ -584,7 +584,7 @@ particular address could be located in any way. Thus an n-way set associative cache will allow a cache line to exist in any entry of a set sized - total blocks mod n — shows a sample + total blocks n — shows a sample 8-element, 4-way set associative cache; in this case the two addresses have four possible locations, meaning only half the cache must be searched upon lookup. The more @@ -655,8 +655,8 @@ Tags need to be checked in parallel to keep -latency times low; more tag bits (i.e. less set associativity) -requires more complex hardware to achieve this. Alternatively more set +latency times low; more tag bits (i.e. more set associativity) +requires more complex hardware to achieve this. Alternatively less set associativity means less tags, but the processor now needs hardware to multiplex the output of the many sets, which can also add latency. @@ -735,7 +735,7 @@ multiplex the output of the many sets, which can also add latency. a separate chip that is part of the motherboard which buffers and communicates interrupt information to the main processor. Each device has a physical interrupt line - between it an one of the PIC's provided by the system. When + between it and one of the PIC's provided by the system. When the device wants to interrupt, it will modify the voltage on this line. A very broad description of the PIC's role is that it @@ -775,9 +775,9 @@ multiplex the output of the many sets, which can also add latency.
Most drivers will split up handling of interrupts into bottom and top - halves. The bottom half will acknowledge the interrupt, queue + halves. The top half will acknowledge the interrupt, queue actions for processing and return the processor to what it was - doing quickly. The top half will then run later when the CPU + doing quickly. The bottom half will then run later when the CPU is free and do the more intensive processing. This is to stop an interrupt hogging the entire CPU.
@@ -836,7 +836,7 @@ multiplex the output of the many sets, which can also add latency. indicate to the PIC that an interrupt has occurred, which it will signal to the operating system for handling. However, if further pulses come in on the already asserted line from - another device. + another device.xxx The issue with level-triggered interrupts is that it may require some considerable amount of time to handle an interrupt for a device. During this time, the interrupt @@ -1030,7 +1030,7 @@ multiplex the output of the many sets, which can also add latency. system. The symmetric term refers to the fact that all the CPUs in the system are the same (e.g. architecture, clock speed). In a - SMP system there are multiple processors that share other all + SMP system there are multiple processors that share all other system resources (memory, disk, etc).
@@ -1463,7 +1463,7 @@ multiplex the output of the many sets, which can also add latency. that is a fence that allows any load or stores to be done before it (move upwards), but nothing before it to move downwards past it. Thus, when load or store with release semantics is - processed, you can be store that any earlier load or stores will + processed, you can be sure that any earlier load or stores will have been complete.
diff --git a/input/chapter03/chapter03.xml b/input/chapter03/chapter03.xml index fe46fa4e..8899ed31 100644 --- a/input/chapter03/chapter03.xml +++ b/input/chapter03/chapter03.xml @@ -289,7 +289,7 @@ simplest case, a small virtual machine monitor can run directly on the hardware and provide an interface to the guest operating systems running on top. This - VMM is often often called a hypervisor (from the word + VMM is often called a hypervisor (from the word "supervisor")In fact, the hypervisor shares much in common with a micro-kernel; both strive to be small layers to present the hardware in a safe fashion to layers @@ -426,7 +426,7 @@ is read(), etc. The Application Binary Interface (ABI) is very similar to an API but rather than being for - software is for hardware. The API will define which register + software is for hardware. The ABI will define which register the system call number should be put in so the kernel can find it when it is asked to do the system call.
@@ -815,7 +815,7 @@ The 386 protection model has four rings, though most operating systems (such as Linux and Windows) only use two of the rings to maintain compatibility with other - architectures that do now allow as many discrete protection + architectures that do not allow as many discrete protection levels. 386 maintains privileges by making each piece of application code running in the system have a small diff --git a/input/chapter04/chapter04.xml b/input/chapter04/chapter04.xml index bdae8a83..f6cd689e 100644 --- a/input/chapter04/chapter04.xml +++ b/input/chapter04/chapter04.xml @@ -274,7 +274,7 @@ brk, so called for the system call which modifies it. By using the brk call to grow the area - downwards the process can request the kernel allocate + upwards the process can request the kernel allocate more memory for it to use. The heap is most commonly managed by the malloc library call. This @@ -506,7 +506,7 @@ provides a level of abstraction in how the Linux kernel can create processes. clone allows you to - explicitly specify which parts of the new process are copied + explicitly specify which parts of the old process are copied into the new process, and which parts are shared between the two processes. This may seem a bit strange at first, but allows us to easily implement threads @@ -778,7 +778,7 @@ UNIX systems assign each process a nice value. The scheduler looks at the nice value and can give priority to those processes that have a - higher "niceness". + less "niceness".
@@ -796,7 +796,7 @@ given increasing inputs. If the algorithm takes twice as long to run for twice as much input, this is increasing linearly. If another algorithm takes four times as long to run given twice as much input, then it is increasing exponentially. Finally if it takes the same -amount of time now matter how much input, then the algorithm runs in +amount of time no matter how much input, then the algorithm runs in constant time. Intuitively you can see that the slower the algorithm grows for more input, the better it is. Computer science text books deal with algorithm analysis in more detail.. diff --git a/input/chapter05/chapter05.xml b/input/chapter05/chapter05.xml index 2eb7672f..e9b2993e 100644 --- a/input/chapter05/chapter05.xml +++ b/input/chapter05/chapter05.xml @@ -34,7 +34,7 @@ to load from stored in a register. For example, registers that are 32 bits wide can hold addresses in a register range from 0x00000000 to - 0xFFFFFFF. + 0xFFFFFFFF. 2^32 is equal to 4GB, so a 32 bit processor can load or store to up to 4GB of memory.
@@ -320,11 +320,11 @@ 64-bit address space. Consider a 64-bit address space divided into 64 KiB pages creates 264/216 = - 252 pages to be managed; assuming + 248 pages to be managed; assuming each page requires an 8-byte pointer to a physical location a total of - 252*23 = - 255 or 32 PiB of contiguous memory + 248*23 = + 251 or 2 PiB of contiguous memory would be required just for the page table! There are ways to split addressing up that avoid this which we will discuss later. @@ -662,7 +662,7 @@ Other page related faults There are two other important faults that the TLB can - generally generate which help to mange accessed and dirty + generally generate which help to manage accessed and dirty pages. Each page generally contains an attribute in the form of a single bit which flags if the page has been accessed or is dirty. @@ -695,7 +695,7 @@ to manage pages. The general concept is that a page has two extra bits; the dirty bit and the accessed bit. When the page is put into the TLB, these bits are set to indicate that the - CPU should raise a fault . + CPU should not raise a fault . When a process tries to reference memory, the hardware does the usual translation process. However, it also does an extra check to see if the accessed flag is @@ -1061,7 +1061,7 @@ resolved by the OS and the processor becomes a software-loaded architecture. However, the performance impact of disabling the HPW is so considerable it is very unlikely any benefit - could be gained from doing so + could be gained from doing so.
Virtual Linear Page-Table diff --git a/input/chapter06/chapter06.xml b/input/chapter06/chapter06.xml index 46f8a316..b00c1101 100644 --- a/input/chapter06/chapter06.xml +++ b/input/chapter06/chapter06.xml @@ -103,7 +103,7 @@ The first step of compiling a source file to an executable file is converting the code from the high level, human understandable language to assembly code. We - know from previous chapters than assembly code works directly with + know from previous chapters that assembly code works directly with the instructions and registers provided by the processor. The compiler is the most complex step of process for a number of reasons. Firstly, humans are very unpredictable and @@ -416,7 +416,7 @@ Inlining functions Similar to unrolling loops, it is possible to put embed - called functions within the callee. The programmer can + called functions within the caller. The programmer can specify that the compiler should try to do this by specifying the function as inline in the function definition. Once again, you may trade code size for @@ -541,7 +541,7 @@ with the prefix extern. extern stands for external and to a human means that this - variable is declared somewhere else. + variable is defined somewhere else. What extern says to a compiler is that it should not allocate any space in memory for this variable, and leave this symbol in the object code where it diff --git a/input/chapter07/chapter07.xml b/input/chapter07/chapter07.xml index a11f4410..b4ffec1d 100644 --- a/input/chapter07/chapter07.xml +++ b/input/chapter07/chapter07.xml @@ -12,7 +12,7 @@ text for historical reasons) and data. We also know, however, an executable does not live its life in memory, but spends most of its life as a - file on a disk waiting to be loaded an run. Since a file is, in + file on a disk waiting to be loaded a run. Since a file is, in essence, simply a contiguous array of bits, all systems come up with methods of organising code and data within files for on-demand execution. This file-format is generally referred to as @@ -605,13 +605,13 @@ (e.g. program.c, which #includes the header file). - We create the library ar + We create the library using ar (short for "archive") command. By convention static library file names are prefixed with lib and have the extension .a. The c argument tells the program - to create the archive, and a + to create the archive, and r tells archive to add the object files specified into the library file.Archives created with ar pop up in a few different places @@ -1034,7 +1034,7 @@ pointer (gp). The ABI specifies that r1 should always contain the gp value for a function. This means that when you call a function, it is the - callees job to save their gp + callers job to save their gp value, set r1 to be the new value (from the function descriptor) and then call the function. diff --git a/input/chapter08/chapter08.xml b/input/chapter08/chapter08.xml index 6bc9dd47..a6362075 100644 --- a/input/chapter08/chapter08.xml +++ b/input/chapter08/chapter08.xml @@ -1040,7 +1040,7 @@ do out of the ordinary operations.x We inspect the symbols with two different tools; in both cases the binding is shown in the second column; the codes - should be quite straight forward (are are documented in the + should be quite straight forward (all are documented in the tools man page).
diff --git a/input/chapter08/code/elfrelocs.txt b/input/chapter08/code/elfrelocs.txt index 2f2c1a0b..b5e33a28 100644 --- a/input/chapter08/code/elfrelocs.txt +++ b/input/chapter08/code/elfrelocs.txt @@ -1,7 +1,7 @@ typedef struct { Elf32_Addr r_offset; <--- address to fix Elf32_Word r_info; <--- symbol table pointer and relocation type -} +} Elf32_Rel typedef struct { Elf32_Addr r_offset;