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b2441318 1# SPDX-License-Identifier: GPL-2.0
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2config STATIC_LINK
3 bool "Force a static link"
4 default n
1da177e4 5 help
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6 This option gives you the ability to force a static link of UML.
7 Normally, UML is linked as a shared binary. This is inconvenient for
8 use in a chroot jail. So, if you intend to run UML inside a chroot,
9 you probably want to say Y here.
10 Additionally, this option enables using higher memory spaces (up to
11 2.75G) for UML.
1da177e4 12
3f22ab27 13source "mm/Kconfig"
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14
15config LD_SCRIPT_STATIC
16 bool
17 default y
42fda663 18 depends on STATIC_LINK
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19
20config LD_SCRIPT_DYN
21 bool
22 default y
23 depends on !LD_SCRIPT_STATIC
39940dbc 24 select MODULE_REL_CRCS if MODVERSIONS
1da177e4 25
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26source "fs/Kconfig.binfmt"
27
28config HOSTFS
29 tristate "Host filesystem"
30 help
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31 While the User-Mode Linux port uses its own root file system for
32 booting and normal file access, this module lets the UML user
33 access files stored on the host. It does not require any
34 network connection between the Host and UML. An example use of
35 this might be:
1da177e4 36
4c9e1385 37 mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
1da177e4 38
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39 where /tmp/fromhost is an empty directory inside UML and
40 /tmp/umlshare is a directory on the host with files the UML user
41 wishes to access.
1da177e4 42
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43 For more information, see
44 <http://user-mode-linux.sourceforge.net/hostfs.html>.
1da177e4 45
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46 If you'd like to be able to work with files stored on the host,
47 say Y or M here; otherwise say N.
1da177e4 48
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49config MCONSOLE
50 bool "Management console"
1eb7c6c7 51 depends on PROC_FS
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52 default y
53 help
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54 The user mode linux management console is a low-level interface to
55 the kernel, somewhat like the i386 SysRq interface. Since there is
56 a full-blown operating system running under every user mode linux
57 instance, there is much greater flexibility possible than with the
58 SysRq mechanism.
1da177e4 59
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60 If you answer 'Y' to this option, to use this feature, you need the
61 mconsole client (called uml_mconsole) which is present in CVS in
62 2.4.5-9um and later (path /tools/mconsole), and is also in the
63 distribution RPM package in 2.4.6 and later.
1da177e4 64
4c9e1385 65 It is safe to say 'Y' here.
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66
67config MAGIC_SYSRQ
68 bool "Magic SysRq key"
69 depends on MCONSOLE
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70 help
71 If you say Y here, you will have some control over the system even
72 if the system crashes for example during kernel debugging (e.g., you
73 will be able to flush the buffer cache to disk, reboot the system
74 immediately or dump some status information). A key for each of the
75 possible requests is provided.
1da177e4 76
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77 This is the feature normally accomplished by pressing a key
78 while holding SysRq (Alt+PrintScreen).
1da177e4 79
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80 On UML, this is accomplished by sending a "sysrq" command with
81 mconsole, followed by the letter for the requested command.
1da177e4 82
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83 The keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
84 unless you really know what this hack does.
1da177e4 85
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86config KERNEL_STACK_ORDER
87 int "Kernel stack size order"
02239c29 88 default 1 if 64BIT
e80ad9b6 89 range 1 10 if 64BIT
02239c29 90 default 0 if !64BIT
1da177e4 91 help
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92 This option determines the size of UML kernel stacks. They will
93 be 1 << order pages. The default is OK unless you're running Valgrind
94 on UML, in which case, set this to 3.
d911202e 95
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96config MMAPPER
97 tristate "iomem emulation driver"
98 help
99 This driver allows a host file to be used as emulated IO memory inside
100 UML.
101
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102config NO_DMA
103 def_bool y
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104
105config PGTABLE_LEVELS
106 int
107 default 3 if 3_LEVEL_PGTABLES
108 default 2
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109
110config SECCOMP
111 def_bool y
112 prompt "Enable seccomp to safely compute untrusted bytecode"
113 ---help---
114 This kernel feature is useful for number crunching applications
115 that may need to compute untrusted bytecode during their
116 execution. By using pipes or other transports made available to
117 the process as file descriptors supporting the read/write
118 syscalls, it's possible to isolate those applications in
119 their own address space using seccomp. Once seccomp is
120 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
121 and the task is only allowed to execute a few safe syscalls
122 defined by each seccomp mode.
123
124 If unsure, say Y.