Add serialization of the fd array when checkpointing in SE mode.
With this patch, host backed files are restored.
Further work needs to be done for restoring other types of
file descriptor.
As the file path saved is relative, on restoration of the checkpoint,
it may fail to open the file if the path is no longer valid.
If it cannot open the file, it will exit the simulation
with a meaningful error message.
Change-Id: I4d0c7cd614a8abaffcae9aba1a28c9fdbc023c5a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/46619
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Several large changes happen in this patch.
The FDEntry class is rewritten so that file descriptors now correspond to
types: 'File' which is normal file-backed file with the file open on the
host machine, 'Pipe' which is a pipe that has been opened on the host machine,
and 'Device' which does not have an open file on the host yet acts as a pseudo
device with which to issue ioctls. Other types which might be added in the
future are directory entries and sockets (off the top of my head).
The FDArray class was create to hold most of the file descriptor handling
that was stuffed into the Process class. It uses shared pointers and
the std::array type to hold the FDEntries mentioned above.
The changes to these two classes needed to be propagated out to the rest
of the code so there were quite a few changes for that. Also, comments were
added where I thought they were needed to help others and extend our
DOxygen coverage.
This patch extends the previous patch's alterations around fd_map. It cleans
up some of the uglier code in the process file and replaces it with a more
concise C++11 version. As part of the changes, the FdMap class is pulled out
of the Process class and receives its own file.
