On Sat 05 Aug 02:58 PDT 2017, Christoph Hellwig wrote: > On Wed, Aug 02, 2017 at 07:57:53PM -0700, Bjorn Andersson wrote: > > The rfsa driver is used for allocating and exposing regions of shared > > memory with remote processors for the purpose of exchanging sector-data > > between the remote filesystem service and its clients. > > Please explain which remote fs this is for, and submit said file system > for inclu??ion. > In the NAND-era of Qualcomm platforms the modem firmware had direct access to the storage media, but with the move to eMMC and the transition of Linux/Android to become the "primary OS" this access was lost. Remaining in the modem firmware is a file system (EFS) for parameter storage et al, but the block layer was replaced with a block-access protocol, "conveniently" called RemoteFS. The protocol is based on a chunk of RAM and a set of messages to transfer sector-data between the storage device and the chunk of RAM. Up until this patch the user space tool that implements the message handler just mapped the reserved memory region though /dev/mem, but this requires /dev/mem access and for the later platforms we need to make a call into TrustZone to provide the remote permission to access this memory region. So we need some code in the kernel to represent this. > Else: NAK as the scheme looks completely brain dead and bonkers. I can rework the commit message in an attempt to better explain the setup and hope you/people find it slightly less bonkers. Does this sound reasonable? Regards, Bjorn -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
