linux-kernel - Re: [PATCH v2 08/12] nova-core: sequencer: Add register opcodes

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Message-ID: <acc56fbb56c3f40119e5a6abf9f13093d7f4c7e7.camel@nvidia.com>
Date: Wed, 5 Nov 2025 23:19:15 +0000
From: Timur Tabi <ttabi@...dia.com>
To: Joel Fernandes <joelagnelf@...dia.com>, John Hubbard <jhubbard@...dia.com>
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Subject: Re: [PATCH v2 08/12] nova-core: sequencer: Add register opcodes

On Wed, 2025-11-05 at 13:55 -0800, John Hubbard wrote:
> > #define nvdev_trace(d,f,a...) nvdev_printk((d), TRACE,   info, f, ##a)
> > #define nvdev_spam(d,f,a...)  nvdev_printk((d),  SPAM,    dbg, f, ##a)
> 
> ...and those are unusable, unfortunately. I've tried.

This works great for me:

modprobe nouveau dyndbg="+p" modeset=1 debug="gsp=spam" config=NvGspRm=1

I get all sequencer messages when I boot with these options.

> ftrace/bpftrace, maybe those are the real way to "trace"...or something
> other than this.

You could say the same thing about most dev_dbg() statements.

I agree that dev_dbg for sequencer commands is excessive, and that implementing new debug levels
just to get sequencer prints is also excessive.  But Nouveau implement nvkm_trace for a reason.  And
we all know that because of ? in Rust, NovaCore does a terrible job at telling us where an error
actually occurred.  So there is a lot of room for improvement.