4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This is a simple fault tolerant write driver.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This boot service protocol only provides fault tolerant write capability for
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync block devices. The protocol has internal non-volatile intermediate storage
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync of the data and private information. It should be able to recover
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync automatically from a critical fault, such as power failure.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The implementation uses an FTW (Fault Tolerant Write) Work Space.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This work space is a memory copy of the work space on the Working Block,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync the size of the work space is the FTW_WORK_SPACE_SIZE bytes.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The work space stores each write record as EFI_FTW_RECORD structure.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The spare block stores the write buffer before write to the target block.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The write record has three states to specify the different phase of write operation.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 1) WRITE_ALLOCATED is that the record is allocated in write space.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The information of write operation is stored in write record structure.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 2) SPARE_COMPLETED is that the data from write buffer is writed into the spare block as the backup.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 3) WRITE_COMPLETED is that the data is copied from the spare block to the target block.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This driver operates the data as the whole size of spare block.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync It first read the SpareAreaLength data from the target block into the spare memory buffer.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Then copy the write buffer data into the spare memory buffer.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Then write the spare memory buffer into the spare block.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Final copy the data from the spare block to the target block.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync To make this drive work well, the following conditions must be satisfied:
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 1. The write NumBytes data must be fit within Spare area.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Offset + NumBytes <= SpareAreaLength
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 2. The whole flash range has the same block size.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 3. Working block is an area which contains working space in its last block and has the same size as spare block.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 4. Working Block area must be in the single one Firmware Volume Block range which FVB protocol is produced on.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 5. Spare area must be in the single one Firmware Volume Block range which FVB protocol is produced on.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 6. Any write data area (SpareAreaLength Area) which the data will be written into must be
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync in the single one Firmware Volume Block range which FVB protocol is produced on.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync 7. If write data area (such as Variable range) is enlarged, the spare area range must be enlarged.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The spare area must be enough large to store the write data before write them into the target range.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync If one of them is not satisfied, FtwWrite may fail.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Usually, Spare area only takes one block. That's SpareAreaLength = BlockSize, NumberOfSpareBlock = 1.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncCopyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncThis program and the accompanying materials
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncare licensed and made available under the terms and conditions of the BSD License
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncwhich accompanies this distribution. The full text of the license may be found at
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncTHE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncWITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Retrive the FVB protocol interface by HANDLE.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param[in] FvBlockHandle The handle of FVB protocol that provides services for
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync reading, writing, and erasing the target block.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param[out] FvBlock The interface of FVB protocol
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The interface information for the specified protocol was returned.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_UNSUPPORTED The device does not support the FVB protocol.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_INVALID_PARAMETER FvBlockHandle is not a valid EFI_HANDLE or FvBlock is NULL.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // To get the FVB protocol interface on the handle
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Retrive the Swap Address Range protocol interface.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param[out] SarProtocol The interface of SAR protocol
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The SAR protocol instance was found and returned in SarProtocol.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_NOT_FOUND The SAR protocol instance was not found.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_INVALID_PARAMETER SarProtocol is NULL.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Locate Swap Address Range protocol
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Function returns an array of handles that support the FVB protocol
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync in a buffer allocated from pool.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param[out] NumberHandles The number of handles returned in Buffer.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param[out] Buffer A pointer to the buffer to return the requested
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync array of handles that support FVB protocol.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The array of handles was returned in Buffer, and the number of
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync handles in Buffer was returned in NumberHandles.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_NOT_FOUND No FVB handle was found.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_OUT_OF_RESOURCES There is not enough pool memory to store the matching results.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_INVALID_PARAMETER NumberHandles is NULL or Buffer is NULL.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Locate all handles of Fvb protocol
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Firmware Volume Block Protocol notification event handler.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param[in] Event Event whose notification function is being invoked.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param[in] Context Pointer to the notification function's context.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Just return to avoid installing FaultTolerantWriteProtocol again
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // if Fault Tolerant Write protocol has been installed.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Found proper FVB protocol and initialize FtwDevice for protocol installation
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Install protocol interface
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This function is the entry point of the Fault Tolerant Write driver.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param[in] ImageHandle A handle for the image that is initializing this driver
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param[in] SystemTable A pointer to the EFI system table
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The initialization finished successfully.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_OUT_OF_RESOURCES Allocate memory error
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_INVALID_PARAMETER Workspace or Spare block does not exist
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Allocate private data structure for FTW protocol and do some initialization
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Register FvbNotificationEvent () notify function.