ELF and threads.

notes/.obsidian/plugins/obsidian-to-anki-plugin/data.json

@@ -1016,7 +1016,7 @@
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     "_journal/2024-12/2024-12-11.md": "e7393c01b44c5b804f86f45b8b899b59",
     "encoding/uri.md": "394abe477b882e1414dd2fb151fea823",
-    "encoding/xml.md": "5b345c09ac60821f88ed5b592e411df6",
+    "encoding/xml.md": "01a66b1a102cccc682f8f1cab0f50bc6",
     "encoding/rdf.md": "f5c2c0156046a9474bae3577e739c5ce",
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     "_journal/2024-12/2024-12-14.md": "d2223f90fd1ce3d82a4fbb6828a1ec56",
@@ -1025,7 +1025,7 @@
     "linkers/object-files.md": "77767f310330b8650a5023dd0522226c",
     "_journal/2024-12-16.md": "d867a62a955f3d080ae25f31464d53c4",
     "_journal/2024-12/2024-12-15.md": "be66c8808d8bb66d4e7b91db7c93c94a",
-    "linkers/elf.md": "64262b8ec7d85bab4bd32a238beac638",
+    "linkers/elf.md": "cc24068cbf2599446b6bc0d1f612c7c5",
     "c17/strings/printf.md": "8b67cfbccaf35dd9488b73e7e5555405",
     "c17/strings/index.md": "3fa6f42967f3cc786740bb8537c62682",
     "_journal/2024-12-17.md": "ae55db66c9835876c4a0343ac0806951",
@@ -1033,7 +1033,12 @@
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-    "_journal/2024-12/2024-12-18.md": "06f32ecf5bc088c6db98476fadfd0b5c"
+    "_journal/2024-12/2024-12-18.md": "06f32ecf5bc088c6db98476fadfd0b5c",
+    "threads/index.md": "28783464146ed09603b477bad4b761bc",
+    "_journal/2024-12-20.md": "2e6b1826035eaa60aeb328f61d9bc976",
+    "_journal/2024-12/2024-12-19.md": "cd09c9e522a3b206b8a3524d615fadd5",
+    "_journal/2024-12-21.md": "51bc26a6ec147bd57e0efffd75c266c6",
+    "_journal/2024-12/2024-12-20.md": "3c896dac68ce1bfb1f28cb7da4325c6c"
   },
   "fields_dict": {
     "Basic": [

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)

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]].

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%%

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.
@@ -451,4 +642,5 @@ END%%
 
 ## Bibliography
 
-* Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+* 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.

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).