Re: [PATCH 03/27] gpu: nova-core: set MCTP transport header version to 1

[Zhi Wang]

On Thu, 20 Aug 2026 19:31:33 -0700
John Hubbard <jhubbard@xxxxxxxxxx> wrote:

No need to reply to each comment. :) Feel free to use whichever
feedback you find helpful. I am just glad I could help a bit.

Z.

> On 8/20/26 2:38 AM, Zhi Wang wrote:
> > On Tue, 18 Aug 2026 20:51:56 -0700
> > John Hubbard <jhubbard@xxxxxxxxxx> wrote:
> > 
> > One nit: might be better to update the doc as well.
> 
> Yes. Agreed. I'll send individual replies to the patch feedback
> as usual, but let me first mention that I've applied all of your 
> and Timur's feedback, 100%, to a -v2 branch already.
> 
> It's passing tests cleanly, so as soon as I make a few more passes
> through it I'll post that. Likely tomorrow.
> 
> thanks,
> John Hubbard
> 
> > 
> > Reviewed-by: Zhi Wang <zhiw@xxxxxxxxxx>
> > 
> > diff --git a/Documentation/gpu/nova/core/fsp.rst
> > b/Documentation/gpu/nova/core/fsp.rst index
> > 52d618d22bb8..60c647181da0 100644 ---
> > a/Documentation/gpu/nova/core/fsp.rst +++
> > b/Documentation/gpu/nova/core/fsp.rst @@ -106,6 +106,8 @@ All FSP
> > messages share a common header format consisting of two 32-bit
> > words:
> >  - Bit 30: EOM (End of Message)
> >  - Bits 29:28: Packet sequence number
> >  - Bits 23:16: Source Endpoint ID
> > +- Bits 15:8: Destination Endpoint ID
> > +- Bits 3:0: MCTP header version (1)
> >  
> >  **NVDM header** (NVIDIA Vendor Defined Message):
> >  
> > 
> > 
> >> FSP requires MCTP transport header version 1. Nova-core leaves
> >> version bits 3:0 at zero, so every CoT and PRC request carries an
> >> invalid transport header.
> >>
> >> Define the version and destination endpoint ID fields. Set the
> >> version to 1 for single-packet requests, and leave the unused
> >> destination endpoint ID at zero.
> >>
> >> Assisted-by: Cursor:claude-opus-5
> >> Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
> >> ---
> >>  drivers/gpu/nova-core/mctp.rs | 14 ++++++++++++--
> >>  1 file changed, 12 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/gpu/nova-core/mctp.rs
> >> b/drivers/gpu/nova-core/mctp.rs index 90c642c91a72..03546213da28
> >> 100644 --- a/drivers/gpu/nova-core/mctp.rs
> >> +++ b/drivers/gpu/nova-core/mctp.rs
> >> @@ -42,13 +42,23 @@ pub(crate) struct MctpHeader(u32) {
> >>          29:28 seq;
> >>          /// Source endpoint ID.
> >>          23:16 seid;
> >> +        /// Destination endpoint ID.
> >> +        15:8 deid;
> >> +        /// MCTP header version.
> >> +        3:0 version;
> >>      }
> >>  }
> >>  
> >>  impl MctpHeader {
> >> -    /// Builds a single-packet MCTP header (`SOM=1`, `EOM=1`,
> >> `SEQ=0`, `SEID=0`).
> >> +    /// MCTP specification version 1.0.
> >> +    const VERSION: u32 = 1;
> >> +
> >> +    /// Builds a single-packet MCTP header (`SOM=1`, `EOM=1`,
> >> `SEQ=0`, `SEID=0`, `VERSION=1`). pub(crate) fn single_packet() ->
> >> Self {
> >> -        Self::zeroed().with_som(true).with_eom(true)
> >> +        Self::zeroed()
> >> +            .with_const_version::<{ Self::VERSION }>()
> >> +            .with_som(true)
> >> +            .with_eom(true)
> >>      }
> >>  
> >>      /// Returns whether this is a complete single-packet message
> >> (`SOM=1` and `EOM=1`).
> > 
> 
> 
>