1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
|
.. SPDX-License-Identifier: GPL-2.0+:
.. index::
single: meminfo (command)
meminfo command
===============
Synopsis
--------
::
meminfo
Description
-----------
The meminfo command shows the amount of memory. If ``CONFIG_CMD_MEMINFO_MAP`` is
enabled, then it also shows the layout of memory used by U-Boot and the region
which is free for use by images.
The layout of memory is set up before relocation, within the init sequence in
``board_init_f()``, specifically the various ``reserve_...()`` functions. This
'reservation' of memory starts from the top of RAM and proceeds downwards,
ending with the stack. This results in the maximum possible amount of memory
being left free for image-loading.
The meminfo command writes the DRAM size, then the rest of its outputs in 5
columns:
Region
Name of the region
Base
Base address of the region, i.e. where it starts in memory
Size
Size of the region, which may be a little smaller than the actual size
reserved, e.g. due to alignment
End
End of the region. The last byte of the region is one lower than the address
shown here
Gap
Gap between the end of this region and the base of the one above
Regions shown are:
video
Memory reserved for video framebuffers. This reservation happens in the
bind() methods of all video drivers which are present before relocation,
so the size depends on that maximum amount of memory which all such drivers
want to reserve. This may be significantly greater than the amount actually
needed, if the display is ultimately set to a smaller resolution or colour
depth than the maximum supported.
code
U-Boot's code and Block-Starting Symbol (BSS) region. Before relocation,
U-Boot copies its code to a high region and sets up a BSS immediately after
that. The size of this region is generally therefore ``__bss_end`` -
``__image_copy_start``
malloc
Contains the malloc() heap. The size of this is set by
``CONFIG_SYS_MALLOC_LEN``.
board_info
Contains the ``bd_info`` structure, with some information about the current
board.
global_data
Contains the global-data structure, pointed to by ``gd``. This includes
various pointers, values and flags which control U-Boot.
devicetree
Contains the flatted devicetree blob (FDT) being used by U-Boot to configure
itself and its devices.
bootstage
Contains the bootstage records, which keep track of boot time as U-Boot
executes. The size of this is determined by
``CONFIG_BOOTSTAGE_RECORD_COUNT``, with each record taking approximately
32 bytes.
bloblist
Contains the bloblist, which is a list of tables and other data created by
U-Boot while executed. The size of this is determined by
``CONFIG_BLOBLIST_SIZE``.
stack
Contains U-Boot's stack, growing downwards from the top. The nominal size of
this region is set by ``CONFIG_STACK_SIZE`` but there is no actual limit
enforced, so the stack can grow behind that. Images should be loaded lower
in memory to avoid any conflict.
free
Free memory, which is available for loading images. The base address of
this is ``gd->ram_base`` which is generally set by ``CFG_SYS_SDRAM_BASE``.
Example
-------
This example shows output with both ``CONFIG_CMD_MEMINFO`` and
``CONFIG_CMD_MEMINFO_MAP`` enabled::
=> meminfo
DRAM: 256 MiB
Region Base Size End Gap
------------------------------------------------
video f000000 1000000 10000000
code ec3a000 3c5d28 efffd28 2d8
malloc 8c38000 6002000 ec3a000 0
board_info 8c37f90 68 8c37ff8 8
global_data 8c37d80 208 8c37f88 8
devicetree 8c33000 4d7d 8c37d7d 3
bootstage 8c32c20 3c8 8c32fe8 18
bloblist 8c32000 400 8c32400 820
stack 7c31ff0 1000000 8c31ff0 10
free 0 7c31ff0 7c31ff0 0
Return value
------------
The return value $? is always 0 (true).
|
