56ce985e7f
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5752 42af7a65-404d-4744-a932-0658087f49c3
38 lines
1.3 KiB
Plaintext
38 lines
1.3 KiB
Plaintext
#
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# For a description of the syntax of this configuration file,
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# see misc/tools/kconfig-language.txt.
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#
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if NUTTX_KERNEL
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comment "System call configuration"
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config SYS_RESERVED
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int "Number of reserved system calls"
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default 0
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---help---
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Kernel system calls may share the same software trapping mechanism
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as other functions used by architecture port. Those software traps
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must be reserved for use exclusively by the architecture. These
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value specifies the number of reserved software traps used by the
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architecture; number of the kernel system calls will begin with this
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number.
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config SYS_NNEST
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int "Number of nested system calls"
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default 2
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---help---
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This is architecture dependent. Most architectures allocate
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resources to manage a fixed, maximum number of nested system calls.
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A nested system call occurs in the following scenario: (1) A non-
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privileged user thread executes a system call, (2) part of the
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system call processing cause a call back into the user space code,
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and (3) the user space code performs another system call.
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In the current design, this can happen only under one condition:
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When the kernel calls back into user space in order to allocate user
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space memory. So it is expected that the maximum nesting level will
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be only 2.
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endif
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