2015-02-26 19:23 GMT+01:00 Andrew Bresticker <abrestic@xxxxxxxxxxxx>: > Hi, > > On Thu, Feb 26, 2015 at 4:37 AM, Daniel Schwierzeck > <daniel.schwierzeck@xxxxxxxxx> wrote: >> 2015-02-26 11:17 GMT+01:00 Paul Burton <paul.burton@xxxxxxxxxx>: >>> On Thu, Feb 19, 2015 at 01:50:23PM +0000, Matthew Fortune wrote: >>>> Hi Daniel, >>>> >>>> The spec for MIPS Unified Hosting Interface is available here: >>>> >>>> http://prplfoundation.org/wiki/MIPS_documentation >>>> >>>> As we have previously discussed, this is an ideal place to >>>> define the handover of device tree data from bootloader to >>>> kernel. Using a0 == -2 and defining which register(s) you >>>> need for the actual data will fit nicely. I'll happily >>>> include whatever is decided into the next version of the spec. >> >> this originates from an off-list discussion some months ago started by >> John Crispin. >> >> (CC +John, Ralf, Jonas, linux-mips) >> >>> >>> (CC +Andrew, Ezequiel, James, James) >>> >>> On the talk of DT handover, this recent patchset adding support for a >>> system doing so to Linux is relevant: >>> >>> http://www.linux-mips.org/archives/linux-mips/2015-02/msg00312.html >>> >>> I'm also working on a system for which I'll need to implement DT >>> handover very soon. It would be very nice if we could agree on some >>> standard way of doing so (and eventually if the code on the Linux side >>> can be generic enough to allow a multiplatform kernel). > > +1. I would like to see this happen as well. > >> to be conformant with UHI I propose $a0 == -2 and $a1 == address of DT >> blob. It is a simple extension and should not interfere with the >> various legacy boot interfaces. >> >> U-Boot mainline code is almost ready for DT handover. I have prepared >> a patch [1] which completes it by implementing my proposal. > > Hmm... we decided to follow the ARM convention here ($a0 = 0, $a1 = > -1, $a2 = physical address of DTB), which is also what the BMIPS > platform (submitted by Kevin) is using for DT handover. Is there > already a platform using the protocol you described? no, but with its publication the MIPS UHI spec is kind of official. AFAIK patches to support UHI in gcc, gdb, U-Boot etc. are already submitted or prepared. Matthew suggested that new boot protocols should be compliant with UHI. I think the ARM convention does not fit to UHI. > It's still early > enough that we could change the DT handover for Pistachio, but it > would be good to agree on something soon. > > Thanks, > Andrew -- - Daniel
