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The VFS library can be used in single-threaded or multi-threaded environments and depending on that, signals are handled by the same thread which uses the VFS library or possibly by a different thread. If a VFS plugin needs to block to wait for a signal, there is currently no way which works reliably in both environments. For this reason, this commit makes the interface of the VFS library nonblocking, similar to the File_system session interface. The most important changes are: - Directories are created and opened with the 'opendir()' function and the directory entries are read with the recently introduced 'queue_read()' and 'complete_read()' functions. - Symbolic links are created and opened with the 'openlink()' function and the link target is read with the 'queue_read()' and 'complete_read()' functions and written with the 'write()' function. - The 'write()' function does not wait for signals anymore. This can have the effect that data written by a VFS library user has not been processed by a file system server yet when the library user asks for the size of the file or closes it (both done with RPC functions at the file system server). For this reason, a user of the VFS library should request synchronization before calling 'stat()' or 'close()'. To make sure that a file system server has processed all write request packets which a client submitted before the synchronization request, synchronization is now requested at the file system server with a synchronization packet instead of an RPC function. Because of this change, the synchronization interface of the VFS library is now split into 'queue_sync()' and 'complete_sync()' functions. Fixes #2399 |
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| README | ||
================================
Genode's Rump Kernel kernel port
================================
This repository contains the Genode version of the [http://wiki.netbsd.org/rumpkernel/ - rump kernel].
The kernel is currently used to gain file-system access from within Genode. In
order to achieve that, a Genode file-system server is located at
_src/server/rump_fs_. For accessing the server through the libc, the _libc_fs_
plugin can be facilitated, which is available in the _libports_ repository.
Building instructions
#####################
In order to build the file-system server, issue
! ./tool/ports/prepare_port dde_rump
from Genode's toplevel directory.
Add
! REPOSITORIES += $(GENODE_DIR)/repos/dde_rump
to your _etc/build.conf_ file of you build directory.
Finally,
! make server/rumps_fs
called from your build directory will build the server. You may also specify
! make run/rump_ext2
to run a simple test scenario.
Configuration
#############
Here is an example snippet that configures the server:
!<start name="rump_fs">
! <resource name="RAM" quantum="8M" />
! <provides><service name="File_system"/></provides>
! <config fs="ext2fs"><default-policy root="/" writeable="yes"/></config>
!</start>
The server is looking for a service that provides a Genode block session. If
there is more than one block session in the system, the block session must be
routed to the right block-session server. The value of the _fs_ attribute of
the _config_ node can be one of the following: _ext2fs_ for EXT2, _cd9660_ for
ISO-9660, or _msdos_ for FAT file-system support. _root_ defines the directory
of the file system as seen as root directory by the client. The server hands
most of its RAM quota to the rump kernel. This means the larger the quota is,
the larger the internal block caches of the rump kernel will be.