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Various rewordings and updates to 2.6.16 reality.

This commit is contained in:
Michael Kerrisk 2006-03-21 05:42:30 +00:00
parent 456ed12f5f
commit 3d5f459509
1 changed files with 40 additions and 19 deletions
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59
man2/unshare.2
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@ -62,7 +62,9 @@ or
.\" CLONE_NEWNS does the same thing in clone(), but CLONE_VM,
.\" CLONE_FS, and CLONE_FILES reverse the action of the clone()
.\" flags of the same name.
This flag has the same effect as the
This flag has the
.I same
effect as the
.BR clone (2)
.B CLONE_NEWNS
flag.
@ -72,25 +74,37 @@ Specifying this flag automatically implies
.B CLONE_FS
as well.
.\" As at 2.6.16, the following forced implications also apply,
.\" although CLONE_THREAD and CLONE_SIGHAND are not yet implemented.
.\" although the relevant flags are not yet implemented.
.\" If CLONE_THREAD is set force CLONE_VM.
.\" If CLONE_VM is set, force CLONE_SIGHAND.
.\" If CLONE_SIGHAND is set and signals are also being shared
.\" (i.e., current->signal->count > 1), force CLONE_THREAD.
.TP
.B CLONE_VM
Reverse the effect of the
.BR clone (2)
.B CLONE_VM
flag.
.RB ( CLONE_VM
is also implicitly set by
.BR vfork (2),
and can be reversed using this
.BR unshare ()
flag.)
Unshare virtual memory, so that the calling process no
longer shares its virtual address space with any other process.
.\"
.\" FIXME . CLONE_VM is not (yet, as at 2.6.16) implemented.
.\" .TP
.\" .B CLONE_VM
.\" Reverse the effect of the
.\" .BR clone (2)
.\" .B CLONE_VM
.\" flag.
.\" .RB ( CLONE_VM
.\" is also implicitly set by
.\" .BR vfork (2),
.\" and can be reversed using this
.\" .BR unshare ()
.\" flag.)
.\" Unshare virtual memory, so that the calling process no
.\" longer shares its virtual address space with any other process.
.PP
Specifying any other bits in
.I flags
is likely to cause compatibility problems if the corresponding
.B CLONE_*
values are implemented in future kernels.
Avoid doing this.
.\" FIXME . Check if a later kernel (e.g., 2.6.17) makes explicit
.\" checks to prevent unimplemented bits being set in 'flags'.
.\"
.PP
If
.I flags
@ -137,13 +151,20 @@ In particular, as at kernel 2.6.16,
.BR unshare ()
does not implement flags that reverse the effects of
.BR CLONE_SIGHAND ,
.\" However we can do unshare(CLONE_SIGHAND) if CLONE_SIGHAND
.\" However, we can do unshare(CLONE_SIGHAND) if CLONE_SIGHAND
.\" was not specified when doing clone(); i.e., unsharing
.\" signal handlers is permitted if we are not actually
.\" sharing signal handlers. mtk
.BR CLONE_SYSVSEM ,
or
.BR CLONE_THREAD .
.BR CLONE_THREAD ,
or
.\" FIXME . check future kernel versions (e.g., 2.6.17)
.\" to see if CLONE_VM gets implemented.
.BR CLONE_VM .
.\" However, as at 2.6.16, we can do unshare(CLONE_VM) if CLONE_VM
.\" was not specified when doing clone(); i.e., unsharing
.\" virtual memory is permitted if we are not actually
.\" sharing virtual memory. mtk
Such functionality may be added in the future, if required.
.\"
.\"9) Future Work