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
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
.. 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. In architectures that support it, it also prints
the mapped pages and their permissions. The latter is architecture specific.
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. If the architecture also supports it,
page table entries will be shown next. Finally the rest of the outputs are
printed 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``.
Aarch64 specific flags
----------------------
More information on the output can be found
Chapter D8 - The AArch64 Virtual Memory System Architecture at
https://developer.arm.com/documentation/ddi0487/latest/
In short, for a stage 1 translation regime the following apply:
* RWX: Pages mapped with Read, Write and Execute permissions
* RO: Pages mapped with Read-Only permissions
* PXN: PXN (Privileged Execute Never) applies to execution at EL1 and above
* UXN: UXN (Unprivileged Execute Never) applies to EL0
Example
-------
This example shows output with both ``CONFIG_CMD_MEMINFO`` and
``CONFIG_CMD_MEMINFO_MAP`` enabled for aarch64 qemu::
DRAM: 8 GiB
Walking pagetable at 000000023ffe0000, va_bits: 40. Using 4 levels
[0x0000023ffe1000] | Table | | |
[0x0000023ffe2000] | Table | | |
[0x00000000000000 - 0x00000008000000] | Block | RWX | Normal | Inner-shareable
[0x00000008000000 - 0x00000040000000] | Block | PXN UXN | Device-nGnRnE | Non-shareable
[0x00000040000000 - 0x00000200000000] | Block | RWX | Normal | Inner-shareable
[0x0000023ffea000] | Table | | |
[0x00000200000000 - 0x0000023f600000] | Block | RWX | Normal | Inner-shareable
[0x0000023ffeb000] | Table | | |
[0x0000023f600000 - 0x0000023f68c000] | Pages | RWX | Normal | Inner-shareable
[0x0000023f68c000 - 0x0000023f74f000] | Pages | RO | Normal | Inner-shareable
[0x0000023f74f000 - 0x0000023f794000] | Pages | PXN UXN RO | Normal | Inner-shareable
[0x0000023f794000 - 0x0000023f79d000] | Pages | PXN UXN | Normal | Inner-shareable
[0x0000023f79d000 - 0x0000023f800000] | Pages | RWX | Normal | Inner-shareable
[0x0000023f800000 - 0x00000240000000] | Block | RWX | Normal | Inner-shareable
[0x00000240000000 - 0x00004000000000] | Block | RWX | Normal | Inner-shareable
[0x0000023ffe3000] | Table | | |
[0x00004010000000 - 0x00004020000000] | Block | PXN UXN | Device-nGnRnE | Non-shareable
[0x0000023ffe4000] | Table | | |
[0x00008000000000 - 0x00010000000000] | Block | PXN UXN | Device-nGnRnE | Non-shareable
Region Base Size End Gap
------------------------------------------------
video 23f7e0000 800000 23ffe0000
code 23f68a000 156000 23f7e0000 0
malloc 23e64a000 1040000 23f68a000 0
board_info 23e649f80 78 23e649ff8 8
global_data 23e649df0 188 23e649f78 8
devicetree 23e549df0 100000 23e649df0 0
bloblist 23e547000 2000 23e549000 df0
stack 23d546ff0 1000000 23e546ff0 10
lmb 23d546ff0 0 23d546ff0 0
lmb 23d543000 3ff0 23d546ff0 0
free 40000000 23d543000 27d543000 ffffffffc0000000
Return value
------------
The return value $? is always 0 (true).
|
