AMC-OS Loader Memory management - Revision history

Kindman: /* Initialization */

2022-09-03T11:26:57Z

Initialization

← Older revision		Revision as of 13:26, 3 September 2022
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	During memory initialization process (<code>AMCOSLDR_InitFirstMegabyte</code>), AMC-OS Loader :		During memory initialization process (<code>AMCOSLDR_InitFirstMegabyte</code>), AMC-OS Loader :
	* looks for EBDA using interrupt 12H and value stored in 0040:000E to get highest pointer in memory [_D]		* looks for EBDA using interrupt 12H and value stored in 0040:000E to get highest pointer in memory [_D]
	* calculates the values of [~~__A~~] to get lowest pointer in memory		* calculates the values of [__C] to get lowest pointer in memory
	* creates a linked list of available blocks of memory (<code>AMCOSLDR_Malloc_Entry</code>)		* creates a linked list of available blocks of memory (<code>AMCOSLDR_Malloc_Entry</code>)
	* initializes two blocks of available memory (marked ''Free for allocation'' in previous table)		* initializes two blocks of available memory (marked ''Free for allocation'' in previous table)

Kindman at 11:25, 3 September 2022

2022-09-03T11:25:41Z

← Older revision		Revision as of 13:25, 3 September 2022
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	* looks for EBDA using interrupt 12H and value stored in 0040:000E to get highest pointer in memory [_D]		* looks for EBDA using interrupt 12H and value stored in 0040:000E to get highest pointer in memory [_D]
	* calculates the values of [__A] to get lowest pointer in memory		* calculates the values of [__A] to get lowest pointer in memory
	* creates a linked list of available blocks of memory (AMCOSLDR_Malloc_Entry)		* creates a linked list of available blocks of memory (<code>AMCOSLDR_Malloc_Entry</code>)
	* initializes two blocks of available memory (marked ''Free for allocation'' in previous table)		* initializes two blocks of available memory (marked ''Free for allocation'' in previous table)

	==Allocation==		==Allocation of 512 bytes or more==
	Three functions are available to AMC-OS Loader for memory allocation :		Three main functions are available to AMC-OS Loader for memory allocation. They wait for the requested size in segment size (16-bytes unit), and returns a segment of memory aligned on 512 bytes boundaries to facilitate disk operations.
	* <code>AMCOSLDR_DefinitiveAlloc</code> : Used to allocate memory that shall stay at this place at the end of the process (used by kernel afterwards). Memory will be taken from bottom of free memory.		* <code>AMCOSLDR_DefinitiveAlloc</code> : Used to allocate memory that shall stay at this place at the end of the process (used by kernel afterwards). Memory will be taken from bottom of free memory.
	* <code>AMCOSLDR_TempAlloc</code> : Used to allocate memory that will be freed at the end of ~~the process (eraseable by kernel afterwards)~~. Memory will be taken from top of free memory.		* <code>AMCOSLDR_TempAlloc</code> : Used to allocate memory that will be freed at the end of AMC-OS Loader. Memory will be taken from top of free memory.
	* <code>AMCOSLDR_VolatileAlloc</code> : Used to allocate memory for immediate use (valid only until a new call to any memory function is made). Memory will be taken from top of free memory.		* <code>AMCOSLDR_VolatileAlloc</code> : Used to allocate memory for immediate use (valid only until a new call to any memory function is made). Memory will be taken from top of free memory. It typically do the same as <code>AMCOSLDR_TempAlloc</code> but do not consider the memory to be really used, so only the two other functions maintain the linked list of available blocks of memory.
	~~All~~ functions ~~waits for~~ the ~~requested size in segment size (16-bytes unit), and returns a segment~~ of memory ~~aligned on 512 bytes boundaries to facilitate disk operations~~.		Temporary allocations are reclaimed by kernel later during <code>INIT_MemoryUsableIn1stMeg</code>.

	~~The two first functions maintains~~ the linked list of available ~~blocks of~~ memory.		== Allocation of less than 512 bytes, "Small allocation" ==
			For definitive allocation of less than 512 bytes, an other function is available. It also waits for the requested size in segment size (16-bytes unit), and returns a 16-byte aligned memory segment.

			* <code>AMCOSLDR_DefinitiveSmallAlloc</code> : Used to allocate memory that shall stay at this place at the end of the process (used by kernel afterwards). Memory will be taken from bottom of free memory. Small allocation is maintained with a linked list of structures { free_size_in_segment ; ptr_next_segment } stored directly in free memory, and starting by pointer stored in <code>AMCOSLDR_SmallAllocSegPtr</code>.

			After AMC-OS Loader has finished, kernel reclaims the available memory later during <code>INIT_MemorySmallocInit</code>.

Kindman at 15:51, 13 April 2020

2020-04-13T15:51:09Z

← Older revision		Revision as of 17:51, 13 April 2020
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	* <code>AMCOSLDR_TempAlloc</code> : Used to allocate memory that will be freed at the end of the process (eraseable by kernel afterwards). Memory will be taken from top of free memory.		* <code>AMCOSLDR_TempAlloc</code> : Used to allocate memory that will be freed at the end of the process (eraseable by kernel afterwards). Memory will be taken from top of free memory.
	* <code>AMCOSLDR_VolatileAlloc</code> : Used to allocate memory for immediate use (valid only until a new call to any memory function is made). Memory will be taken from top of free memory.		* <code>AMCOSLDR_VolatileAlloc</code> : Used to allocate memory for immediate use (valid only until a new call to any memory function is made). Memory will be taken from top of free memory.
	All functions waits for the requested size in ~~bytes~~ (~~must be a multiple of~~ 16), and returns a segment of memory aligned on 512 bytes boundaries to facilitate disk operations.		All functions waits for the requested size in segment size (16-bytes unit), and returns a segment of memory aligned on 512 bytes boundaries to facilitate disk operations.

	The two first functions maintains the linked list of available blocks of memory.		The two first functions maintains the linked list of available blocks of memory.

Kindman at 15:15, 13 April 2020

2020-04-13T15:15:52Z

← Older revision		Revision as of 17:15, 13 April 2020
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	* <code>AMCOSLDR_TempAlloc</code> : Used to allocate memory that will be freed at the end of the process (eraseable by kernel afterwards). Memory will be taken from top of free memory.		* <code>AMCOSLDR_TempAlloc</code> : Used to allocate memory that will be freed at the end of the process (eraseable by kernel afterwards). Memory will be taken from top of free memory.
	* <code>AMCOSLDR_VolatileAlloc</code> : Used to allocate memory for immediate use (valid only until a new call to any memory function is made). Memory will be taken from top of free memory.		* <code>AMCOSLDR_VolatileAlloc</code> : Used to allocate memory for immediate use (valid only until a new call to any memory function is made). Memory will be taken from top of free memory.
			All functions waits for the requested size in bytes (must be a multiple of 16), and returns a segment of memory aligned on 512 bytes boundaries to facilitate disk operations.

	The two first functions maintains the linked list of available blocks of memory.		The two first functions maintains the linked list of available blocks of memory.
	~~All function waits for the requested size in bytes (must be a multiple of 16), and returns a segment of memory aligned on 512 bytes boundaries to facilitate disk operations.~~

Kindman at 15:15, 13 April 2020

2020-04-13T15:15:18Z

← Older revision		Revision as of 17:15, 13 April 2020
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	* <code>AMCOSLDR_VolatileAlloc</code> : Used to allocate memory for immediate use (valid only until a new call to any memory function is made). Memory will be taken from top of free memory.		* <code>AMCOSLDR_VolatileAlloc</code> : Used to allocate memory for immediate use (valid only until a new call to any memory function is made). Memory will be taken from top of free memory.
	The two first functions maintains the linked list of available blocks of memory.		The two first functions maintains the linked list of available blocks of memory.
			All function waits for the requested size in bytes (must be a multiple of 16), and returns a segment of memory aligned on 512 bytes boundaries to facilitate disk operations.

Kindman at 15:12, 13 April 2020

2020-04-13T15:12:42Z

← Older revision		Revision as of 17:12, 13 April 2020
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	\|<code>9[_D]-09FFF</code>		\|<code>9[_D]-09FFF</code>
	\|Extended BIOS data area (EBDA - optional)		\|Extended BIOS data area (EBDA - optional)
	}		\|}

	=Memory management=		=Memory management=
	==Initialization==		==Initialization==

Kindman at 15:11, 13 April 2020

2020-04-13T15:11:58Z

← Older revision		Revision as of 17:11, 13 April 2020
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	=Memory used during AMC-OS Loader execution=		=Memory used during AMC-OS Loader execution=
	AMC-OS Loader uses only the first megabyte of memory :		AMC-OS Loader uses only the first megabyte of memory :
	*<code>00000-003FF</code> : Real-mode interrupt table		{\|-
	*<code>00400-00500</code> : BIOS static data		\|<code>00000-003FF</code>
	*<code>00501-005FF</code> : Free (unused)		\|Real-mode interrupt table
	*<code>00600-007FF</code> : ''Master boot record''		\|-
	*<code>00800-[__A]</code> : Kernel static data (initialized by boot loader)		\|<code>00400-00500</code>
	*<code>[__A]-[__B]</code> : AMC-OS Loader code		\|BIOS static data
	*<code>[__B]-[__C]</code> : AMC-OS Loader picture		\|-
	*<code>[__C]-077FF</code> : ''Free for allocation''		\|<code>00501-005FF</code>
	*<code>077FF-07BFF</code> : AMC-OS Loader stack		\|Free (unused)
	*<code>07C00-07DFF</code> : Boot loader code (VBR or MBR for floppy disk)		\|-
	*<code>07E00-07FFF</code> : Free (unused)		\|<code>00600-007FF</code>
	*<code>08000-9[_D]</code> : ''Free for allocation''		\|''Master boot record''
	*<code>9[_D]-09FFF</code> : Extended BIOS data area (EBDA - optional)		\|-
			\|<code>00800-[__A]</code>
			\|Kernel static data (initialized by boot loader)
			\|-
			\|<code>[__A]-[__B]</code>
			\|AMC-OS Loader code
			\|-
			\|<code>[__B]-[__C]</code>
			\|AMC-OS Loader picture
			\|-
			\|<code>[__C]-077FF</code>
			\|''Free for allocation''
			\|-
			\|<code>077FF-07BFF</code>
			\|AMC-OS Loader stack
			\|-
			\|<code>07C00-07DFF</code>
			\|Boot loader code (VBR or MBR for floppy disk)
			\|-
			\|<code>07E00-07FFF</code>
			\|Free (unused)
			\|-
			\|<code>08000-9[_D]</code>
			\|''Free for allocation''
			\|-
			\|<code>9[_D]-09FFF</code>
			\|Extended BIOS data area (EBDA - optional)
			}
	=Memory management=		=Memory management=
	==Initialization==		==Initialization==

Kindman: Created page with "=Memory used during AMC-OS Loader execution= AMC-OS Loader uses only the first megabyte of memory : `00000-003FF` : Real-mode interrupt table 00400-00500 2020-04-13T15:08:53Z Created page with "=Memory used during AMC-OS Loader execution= AMC-OS Loader uses only the first megabyte of memory : <code>00000-003FF</code> : Real-mode interrupt table <code>00400-00500</c..." New page =Memory used during AMC-OS Loader execution= AMC-OS Loader uses only the first megabyte of memory : <code>00000-003FF</code> : Real-mode interrupt table <code>00400-00500</code> : BIOS static data <code>00501-005FF</code> : Free (unused) <code>00600-007FF</code> : ''Master boot record'' <code>00800-[A]</code> : Kernel static data (initialized by boot loader) <code>[A]-[B]</code> : AMC-OS Loader code <code>[B]-[C]</code> : AMC-OS Loader picture <code>[C]-077FF</code> : ''Free for allocation'' <code>077FF-07BFF</code> : AMC-OS Loader stack <code>07C00-07DFF</code> : Boot loader code (VBR or MBR for floppy disk) <code>07E00-07FFF</code> : Free (unused) <code>08000-9[_D]</code> : ''Free for allocation'' <code>9[_D]-09FFF</code> : Extended BIOS data area (EBDA - optional) =Memory management= ==Initialization== During memory initialization process (<code>AMCOSLDR_InitFirstMegabyte</code>), AMC-OS Loader : looks for EBDA using interrupt 12H and value stored in 0040:000E to get highest pointer in memory [_D] * calculates the values of [__A] to get lowest pointer in memory * creates a linked list of available blocks of memory (AMCOSLDR_Malloc_Entry) * initializes two blocks of available memory (marked ''Free for allocation'' in previous table) ==Allocation== Three functions are available to AMC-OS Loader for memory allocation : * <code>AMCOSLDR_DefinitiveAlloc</code> : Used to allocate memory that shall stay at this place at the end of the process (used by kernel afterwards). Memory will be taken from bottom of free memory. * <code>AMCOSLDR_TempAlloc</code> : Used to allocate memory that will be freed at the end of the process (eraseable by kernel afterwards). Memory will be taken from top of free memory. * <code>AMCOSLDR_VolatileAlloc</code> : Used to allocate memory for immediate use (valid only until a new call to any memory function is made). Memory will be taken from top of free memory. The two first functions maintains the linked list of available blocks of memory.