ELF and threads.

2024-12-21 09:37:59 -07:00 · 2024-12-21 09:37:59 -07:00 · b314d47f3c
parent 5bb40f0018
commit b314d47f3c
7 changed files with 263 additions and 6 deletions
--- a/notes/.obsidian/plugins/obsidian-to-anki-plugin/data.json
+++ b/notes/.obsidian/plugins/obsidian-to-anki-plugin/data.json
@ -1016,7 +1016,7 @@
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-    "linkers/elf.md": "64262b8ec7d85bab4bd32a238beac638",
+    "linkers/elf.md": "cc24068cbf2599446b6bc0d1f612c7c5",
    "c17/strings/printf.md": "8b67cfbccaf35dd9488b73e7e5555405",
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+    "_journal/2024-12/2024-12-18.md": "06f32ecf5bc088c6db98476fadfd0b5c",
+    "threads/index.md": "28783464146ed09603b477bad4b761bc",
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  "fields_dict": {
    "Basic": [
--- a/notes/_journal/2024-12-21.md
+++ b/notes/_journal/2024-12-21.md
@ -0,0 +1,9 @@
+---
+title: "2024-12-21"
+---
+
+- [x] Anki Flashcards
+- [x] KoL
+- [x] OGS
+- [ ] Sheet Music (10 min.)
+- [ ] Korean (Read 1 Story)
--- a/notes/_journal/2024-12/2024-12-19.md
+++ b/notes/_journal/2024-12/2024-12-19.md
--- a/notes/_journal/2024-12/2024-12-20.md
+++ b/notes/_journal/2024-12/2024-12-20.md
@ -0,0 +1,11 @@
+---
+title: "2024-12-20"
+---
+
+- [x] Anki Flashcards
+- [x] KoL
+- [x] OGS
+- [ ] Sheet Music (10 min.)
+- [ ] Korean (Read 1 Story)
+
+* Initial notes on [[threads/index|thread-local storage]].
--- a/notes/encoding/xml.md
+++ b/notes/encoding/xml.md
@ -249,7 +249,7 @@ Which namespace is attribute `b` a member of?
  <bar a="1" p:b="2" />
 </foo>
 ```
-Back: `p`
+Back: `ns1`
 Reference: “XML Namespace,” in _Wikipedia_, April 11, 2024, [https://en.wikipedia.org/w/index.php?title=XML_namespace](https://en.wikipedia.org/w/index.php?title=XML_namespace&oldid=1218316095).
 <!--ID: 1733842094375-->
 END%%
--- a/notes/linkers/elf.md
+++ b/notes/linkers/elf.md
@ -156,6 +156,7 @@ Basic
 What kind of global/static C variables does the `.data` section of an ELF file contain?
 Back: Those initialized to a non-zero value.
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734368832070-->
 END%%

@ -164,6 +165,7 @@ Basic
 Which ELF section contains global C variables initialized to a non-zero value?
 Back: `.data`
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734368832073-->
 END%%

@ -172,6 +174,7 @@ Basic
 Which ELF section contains static C variables initialized to a non-zero value?
 Back: `.data`
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734368832075-->
 END%%

@ -180,6 +183,7 @@ Basic
 Which ELF section contains local C variables initialized to a non-zero value?
 Back: N/A.
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734368832076-->
 END%%

@ -191,6 +195,7 @@ int foo = 1;
 ```
 Back: `.data`
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734369188095-->
 END%%

@ -204,6 +209,7 @@ int foo() {
 ```
 Back: N/A.
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734369188101-->
 END%%

@ -217,9 +223,81 @@ int foo() {
 ```
 Back: `.data`.
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734369188110-->
 END%%

+### `.tdata`
+
+Thread-local global and static C variables initialized to a non-zero value.
+
+%%ANKI
+Basic
+What kind of global/static C variables does the `.tdata` section of an ELF file contain?
+Back: Thread-local variables initialized to a non-zero value.
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402941-->
+END%%
+
+%%ANKI
+Basic
+Which ELF section contains global thread-local C variables initialized to a non-zero value?
+Back: `.tdata`
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402945-->
+END%%
+
+%%ANKI
+Basic
+Which ELF section contains static thread-local C variables initialized to a non-zero value?
+Back: `.tdata`
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402949-->
+END%%
+
+%%ANKI
+Basic
+Consider the following translation unit. Which ELF section will `foo` end up in?
+```c
+_Thread_local int foo = 1;
+```
+Back: `.tdata`
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402952-->
+END%%
+
+%%ANKI
+Basic
+Consider the following translation unit. Which ELF section will `bar` end up in?
+```c
+int foo() {
+  static _Thread_local int bar = 1;
+}
+```
+Back: `.tdata`.
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402957-->
+END%%
+
+%%ANKI
+Basic
+Consider the following translation unit. Which ELF section will `bar` end up in?
+```c
+int foo() {
+  _Thread_local int bar = 1;
+}
+```
+Back: N/A. Compilation error - `bar` must have global storage.
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402961-->
+END%%
+
 ### `.bss`

 Uninitialized global and static C variables, along with any global or static variables initialized to zero.
@ -229,6 +307,7 @@ Basic
 What kind of global/static C variables does the `.bss` section of an ELF file contain?
 Back: Unitialized variables or those initialized to zero.
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734368832077-->
 END%%

@ -237,6 +316,7 @@ Basic
 Which ELF section contains uninitialized global C variables?
 Back: `.bss`
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734368832078-->
 END%%

@ -245,6 +325,7 @@ Basic
 Which ELF section contains global C variables initialized to a zero value?
 Back: `.bss`
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734368832079-->
 END%%

@ -253,6 +334,7 @@ Basic
 Which two ELF sections contain global/static C variables?
 Back: `.data` and `.bss`
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734368832080-->
 END%%

@ -264,6 +346,7 @@ int foo = 0;
 ```
 Back: `.bss`
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734369188113-->
 END%%

@ -275,14 +358,16 @@ int foo;
 ```
 Back: `.bss`
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734369188117-->
 END%%

 %%ANKI
 Basic
 Both `.bss` and `.data` hold what kind of C variables?
-Back: Global or static C variables.
+Back: Global or static variables.
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734369188121-->
 END%%

@ -328,9 +413,115 @@ int foo() {
 ```
 Back: `.bss`.
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c17
 <!--ID: 1734369188106-->
 END%%

+### `.tbss`
+
+Uninitialized global and static thread-local C variables, along with any global or static thread-local variables initialized to zero.
+
+%%ANKI
+Basic
+What kind of global/static C variables does the `.tbss` section of an ELF file contain?
+Back: Unitialized thread-local variables or those initialized to zero.
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402964-->
+END%%
+
+%%ANKI
+Basic
+Which ELF section contains uninitialized thread-local global C variables?
+Back: `.tbss`
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402968-->
+END%%
+
+%%ANKI
+Basic
+Which ELF section contains global thread-local C variables initialized to a zero value?
+Back: `.tbss`
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402971-->
+END%%
+
+%%ANKI
+Basic
+Which two ELF sections contain global/static thread-local C variables?
+Back: `.tdata` and `.bss`
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402975-->
+END%%
+
+%%ANKI
+Basic
+Consider the following translation unit. Which ELF section will `foo` end up in?
+```c
+_Thread_local int foo = 0;
+```
+Back: `.tbss`
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402980-->
+END%%
+
+%%ANKI
+Basic
+Consider the following translation unit. Which ELF section will `foo` end up in?
+```c
+_Thread_local int foo;
+```
+Back: `.tbss`
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402984-->
+END%%
+
+%%ANKI
+Basic
+Both `.tbss` and `.tdata` hold what kind of C variables?
+Back: Global or static thread-local variables.
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402989-->
+END%%
+
+%%ANKI
+Basic
+Which of `.tdata` and/or `.tbss` is considered a "placeholder"?
+Back: `.tbss`
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402993-->
+END%%
+
+%%ANKI
+Basic
+How does the size of the `.tbss` section compare to that of the `.tdata` section?
+Back: Less than or equal since the `.tbss` section is always empty.
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745402997-->
+END%%
+
+%%ANKI
+Basic
+Consider the following translation unit. Which ELF section will `bar` end up in?
+```c
+int foo() {
+  static _Thread_local int bar = 0;
+}
+```
+Back: `.tbss`.
+Reference: Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
+Tags: c17
+<!--ID: 1734745403003-->
+END%%
+
 ### `.symtab`

 A symbol table with information about functions and global variables defined and referenced in the program.
@ -452,3 +643,4 @@ END%%
 ## Bibliography

 * Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+* Ulrich Drepper, “ELF Handling For Thread-Local Storage,” n.d.
--- a/notes/threads/index.md
+++ b/notes/threads/index.md
@ -0,0 +1,40 @@
+---
+title: Threads
+TARGET DECK: Obsidian::STEM
+FILE TAGS: threads
+tags:
+  - threads
+---
+
+## Overview
+
+**Thread-Local Storage** (TLS) is a memory management method that uses static or global memory local to a thread. In C17, the keyword `_Thread_local` is used for defining thread-local variables.
+
+%%ANKI
+Basic
+In the context of memory management, what is TLS an acronym for?
+Back: **T**hread-**L**ocal **S**torage.
+Reference: “Thread-Local Storage,” in _Wikipedia_, October 21, 2024, [https://en.wikipedia.org/w/index.php?title=Thread-local_storage](https://en.wikipedia.org/w/index.php?title=Thread-local_storage&oldid=1252543227).
+<!--ID: 1734745402895-->
+END%%
+
+%%ANKI
+Basic
+What storage class specifier is used to modify TLS?
+Back: `_Thread_local`
+Reference: “Thread-Local Storage,” in _Wikipedia_, October 21, 2024, [https://en.wikipedia.org/w/index.php?title=Thread-local_storage](https://en.wikipedia.org/w/index.php?title=Thread-local_storage&oldid=1252543227).
+Tags: c17
+<!--ID: 1734745402931-->
+END%%
+
+%%ANKI
+Basic
+What is thread-local storage?
+Back: A memory management method that uses static or global memory local to a thread.
+Reference: “Thread-Local Storage,” in _Wikipedia_, October 21, 2024, [https://en.wikipedia.org/w/index.php?title=Thread-local_storage](https://en.wikipedia.org/w/index.php?title=Thread-local_storage&oldid=1252543227).
+<!--ID: 1734745402937-->
+END%%
+
+## Bibliography
+
+* “Thread-Local Storage,” in _Wikipedia_, October 21, 2024, [https://en.wikipedia.org/w/index.php?title=Thread-local_storage](https://en.wikipedia.org/w/index.php?title=Thread-local_storage&oldid=1252543227).