| commit | 52a8319658c8ac3dcce2fed116d20d6014d7b143 | [log] [tgz] |
|---|---|---|
| author | Andrew Jeffery <andrew@aj.id.au> | Tue Mar 27 10:35:31 2018 +1030 |
| committer | Andrew Jeffery <andrew@aj.id.au> | Wed Apr 04 17:27:31 2018 +0930 |
| tree | c546f26c8d07e3284828b09d85574d3806cd1c1c | |
| parent | 943aba060f143667d502792f11e95f42bc7da346 [diff] |
vpnor: Add handler for CREATE_WRITE_WINDOW
The virtual PNOR implementation enforces the read-only attribute of FFS
partitions, which is a departure from how things were handled
previously. In the past it was purely up to the host to respect the
flags set on the partition, but nothing prevented the host from
modifying it. Now it's possible for errors to occur when the host
attempts to flush changes back to the flash: mboxd can deny the change.
This denial can happen in a number of circumstances:
1. An explicit WRITE_FLUSH command from the host
2. An implicit WRITE_FLUSH via an explicit CLOSE_WINDOW command
3. An implicit WRITE_FLUSH via CREATE_{READ,WRITE}_WINDOW, which happens
via the implicit CLOSE_WINDOW
All of these attempts will fail if the write to the currently open
window cannot be allowed to succeed. Failing to open a read window due
to failure to flush pending writes is particularly painful, as we are
not able to ever successfully open a window again.
Instead, detect when the host attempts to open a write window over a
anything but a writeable partition. If this case is detected, return an
error for the CREATE_WRITE_WINDOW operation to prevent systemic failures
later on.
Change-Id: I991b6f1570d9b1b384b1024e3bd8a77e5efcd198
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Copyright 2017 IBM
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
This repo contains the protocol definition for the host to BMC mailbox communication specification which can be found in Documentation/mbox_procotol.md.
There is also a reference implementation of a BMC mailbox daemon, the details of which can be found in Documentation/mboxd.md.
Finally there is also an implementation of a mailbox daemon control program, the details of which can be found in Documentation/mboxctl.md.
This codebase is a mix of C (due to its heritage) and C++. This is an ugly split: message logging and error handling can be vastly different inside the same codebase. The aim is to remove the split one way or the other over time and have consistent approaches to solving problems.
phosphor-mboxd is developed as part of the OpenBMC project, which also leads to integration of frameworks such as phosphor-logging. Specifically on phosphor-logging, it's noted that without care we can achieve absurd duplication or irritating splits in where errors are reported, as the C code is not capable of making use of the interfaces provided.
Message logging MUST be done to stdout or stderr, and MUST NOT be done directly via journal APIs or wrappers of the journal APIs.
Rationale:
We have two scenarios where we care about output, with the important restriction that the method must be consistent between C and C++:
In the first case it is desirable that the messages appear in the system journal. To this end, systemd will by default capture stdout and stderr of the launched binary and redirect it to the journal.
In the second case it is desirable that messages be captured by the test runner (make check) for test failure analysis, and it is undesirable for messages to appear in the system journal (as these are tests, not issues affecting the health of the system they are being executed on).
Therefore direct calls to the journal MUST be avoided for the purpose of message logging.
Note: This section specifically targets the use of phosphor-logging's log<T>(). It does not prevent the use of elog<T>().