[PATCH v9 0/4] gpu: nova: add boot42 support for next-gen GPUs

[PATCH v9 0/4] gpu: nova: add boot42 support for next-gen GPUs

[John Hubbard]

Changes in v9:

1) Simplified the Revision updates, so that Revision's member fields can
   remain private (thanks to Alex Courbot).

2) Restore a missing documentation comment line for chipset().

3) Removed the patch that changed from ENODEV to ENOTSUPP, and used
   ENODEV to mean "GPU is not supported", because the driver core
   expects that specific error code.

4) Rebased onto drm-rust-next, which already has patch 1/1 from v8, so
   that one no longer appears in v9.

Changes in v8:

1) Added two new patches: convert the remaining ENODEV cases to ENOTSUPP,
   and add dev_err!() report for some (most) cases of unsupported GPUs.

2) Corrected some comments.

3) Added Joel's Reviewed-by, but not yet to the two new patches.

Changes in v7:

1) Added a TODO to eventually remove the Default trait from Architecture.
2) Further refined the logic and comments for reading boot0, then boot42.

Changes in v6:

1) Split out a separate patch for implementing Display for Spec.
2) Moved Spec implementation code to its proper location.
3) Significantly changed the use_boot42_instead() logic, and updated the
   comments accordingly.
4) Fixed the boot42 register and field values, which were wrong (and
   had not been exercised before).
5) Imported Revision, to save a few ::'s.
6) Rebased to the very latest drm-rust-next, which now includes the new
   "one 'use' item per line" updates.

Changes in v5:

Two fixes, both from Timur's review feedback (thanks!):

1) Updated both the cover letter, and patch 3 commit description, with
the correct description of the future contents of NV_PMC_BOOT_0.
2) Removed a trailing "boot42" typo from a comment in the code.

Changes in v4:

1) Simplified and improved the decision logic: reads both arch_0 and
arch_1 fields in boot0, and skips the unnecessary is_nv04() logic as
well. Thanks to Timur Tabi and Danilo for noticing these issues.
2) Added a patch to represent Architecture as a u8. This simplifies a
few things. (Thanks to Alex Courbot. I added your Suggested-by to that
patch.)
3) Enhanced the Revision type to do more, which simplifies the callers.
(Thanks to Danilo.)

Changes in v3:

1) Restored the Revision type as recommended by Danilo, but decoupled it
from boot0.
2) Applied Alex Courbot's suggestion to use TryFrom<NV_PMC_BOOT_0/42>
for Spec.
3) Reflowed the new comment documentation to 100 cols, to avoid wasting
a few vertical lines.

Changes in v2:

1) Restored the Spec type, and used that to encapsulate the subsequent
   boot42 enhancements. Thanks to Danilo Krummrich's feedback for that
   improvement.

v1 cover letter (with typos fixed)

NVIDIA GPUs are moving away from using NV_PMC_BOOT_0 to contain
architecture and revision details, and will instead use NV_PMC_BOOT_42
in the future. NV_PMC_BOOT_0 will contain a specific set of values that
will mean "go read NV_PMC_BOOT_42 instead".

Change the selection logic in Nova so that it will claim Turing and
later GPUs. This will work for the foreseeable future, without any
further code changes here, because all NVIDIA GPUs are considered, from
the oldest supported on Linux (NV04), through the future GPUs.

Add some comment documentation to explain, chronologically, how boot0
and boot42 change with the GPU eras, and how that affects the selection
logic.

Also, remove the Revision type, because Revision is no longer valuable
as a stand-alone type, because we only ever want the full information
that Spec provides.

This is based on today's drm-rust-next, which in turn is based on
Linux 6.18-rc2.

John Hubbard (4):
  gpu: nova-core: prepare Spec and Revision types for boot0/boot42
  gpu: nova-core: make Architecture behave as a u8 type
  gpu: nova-core: add boot42 support for next-gen GPUs
  gpu: nova-core: provide a clear error report for unsupported GPUs

 drivers/gpu/nova-core/gpu.rs  | 72 ++++++++++++++++++++++++++++++-----
 drivers/gpu/nova-core/regs.rs | 39 ++++++++++++++++---
 2 files changed, 97 insertions(+), 14 deletions(-)


base-commit: 38b7cc448a5b6772cad2b853a011f507ad95306a
-- 
2.51.2

[PATCH v9 1/4] gpu: nova-core: prepare Spec and Revision types for boot0/boot42

[John Hubbard]

Allow a both Revision and Spec to be constructed directly from a
NV_PMC_BOOT_0 register.

Also, slightly enhance the comment about Spec, to be more precise.

Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Timur Tabi <ttabi@nvidia.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/gpu/nova-core/gpu.rs | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index dfeba9d5d8f6..57c20d1e7274 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -147,8 +147,8 @@ pub(crate) struct Revision {
     minor: u8,
 }
 
-impl Revision {
-    fn from_boot0(boot0: regs::NV_PMC_BOOT_0) -> Self {
+impl From<regs::NV_PMC_BOOT_0> for Revision {
+    fn from(boot0: regs::NV_PMC_BOOT_0) -> Self {
         Self {
             major: boot0.major_revision(),
             minor: boot0.minor_revision(),
@@ -162,10 +162,9 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     }
 }
 
-/// Structure holding the metadata of the GPU.
+/// Structure holding a basic description of the GPU: `Chipset` and `Revision`.
 pub(crate) struct Spec {
     chipset: Chipset,
-    /// The revision of the chipset.
     revision: Revision,
 }
 
@@ -173,9 +172,17 @@ impl Spec {
     fn new(bar: &Bar0) -> Result<Spec> {
         let boot0 = regs::NV_PMC_BOOT_0::read(bar);
 
+        Spec::try_from(boot0)
+    }
+}
+
+impl TryFrom<regs::NV_PMC_BOOT_0> for Spec {
+    type Error = Error;
+
+    fn try_from(boot0: regs::NV_PMC_BOOT_0) -> Result<Self> {
         Ok(Self {
             chipset: boot0.chipset()?,
-            revision: Revision::from_boot0(boot0),
+            revision: boot0.into(),
         })
     }
 }
-- 
2.51.2

[PATCH v9 2/4] gpu: nova-core: make Architecture behave as a u8 type

[John Hubbard]

This allows Architecture to be passed into register!() and bitfield!()
macro calls. That in turn requires a default implementation for
Architecture.

This simplifies transforming BOOT0 (and later, BOOT42) register values
into GPU architectures.

Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Timur Tabi <ttabi@nvidia.com>
Suggested-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/gpu/nova-core/gpu.rs | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 57c20d1e7274..88a6d7af9f37 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -122,8 +122,14 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 }
 
 /// Enum representation of the GPU generation.
-#[derive(fmt::Debug)]
+///
+/// TODO: remove the `Default` trait implementation, and the `#[default]`
+/// attribute, once the register!() macro (which creates Architecture items) no
+/// longer requires it for read-only fields.
+#[derive(fmt::Debug, Default, Copy, Clone)]
+#[repr(u8)]
 pub(crate) enum Architecture {
+    #[default]
     Turing = 0x16,
     Ampere = 0x17,
     Ada = 0x19,
@@ -142,6 +148,13 @@ fn try_from(value: u8) -> Result<Self> {
     }
 }
 
+impl From<Architecture> for u8 {
+    fn from(value: Architecture) -> Self {
+        // CAST: `Architecture` is `repr(u8)`, so this cast is always lossless.
+        value as u8
+    }
+}
+
 pub(crate) struct Revision {
     major: u8,
     minor: u8,
-- 
2.51.2

[PATCH v9 3/4] gpu: nova-core: add boot42 support for next-gen GPUs

[John Hubbard]

NVIDIA GPUs are moving away from using NV_PMC_BOOT_0 to contain
architecture and revision details, and will instead use NV_PMC_BOOT_42
in the future. NV_PMC_BOOT_0 will contain a specific set of values
that will mean "go read NV_PMC_BOOT_42 instead".

Change the selection logic in Nova so that it will claim Turing and
later GPUs. This will work for the foreseeable future, without any
further code changes here, because all NVIDIA GPUs are considered, from
the oldest supported on Linux (NV04), through the future GPUs.

Add some comment documentation to explain, chronologically, how boot0
and boot42 change with the GPU eras, and how that affects the selection
logic.

Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Timur Tabi <ttabi@nvidia.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/gpu/nova-core/gpu.rs  | 41 ++++++++++++++++++++++++++++++-----
 drivers/gpu/nova-core/regs.rs | 21 +++++++++++++-----
 2 files changed, 52 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 88a6d7af9f37..8e04628ca3d9 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -169,6 +169,15 @@ fn from(boot0: regs::NV_PMC_BOOT_0) -> Self {
     }
 }
 
+impl From<regs::NV_PMC_BOOT_42> for Revision {
+    fn from(boot0: regs::NV_PMC_BOOT_42) -> Self {
+        Self {
+            major: boot0.major_revision(),
+            minor: boot0.minor_revision(),
+        }
+    }
+}
+
 impl fmt::Display for Revision {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{:x}.{:x}", self.major, self.minor)
@@ -183,19 +192,41 @@ pub(crate) struct Spec {
 
 impl Spec {
     fn new(bar: &Bar0) -> Result<Spec> {
+        // Some brief notes about boot0 and boot42, in chronological order:
+        //
+        // NV04 through NV50:
+        //
+        //    Not supported by Nova. boot0 is necessary and sufficient to identify these GPUs.
+        //    boot42 may not even exist on some of these GPUs.
+        //
+        // Fermi through Volta:
+        //
+        //     Not supported by Nova. boot0 is still sufficient to identify these GPUs, but boot42
+        //     is also guaranteed to be both present and accurate.
+        //
+        // Turing and later:
+        //
+        //     Supported by Nova. Identified by first checking boot0 to ensure that the GPU is not
+        //     from an earlier (pre-Fermi) era, and then using boot42 to precisely identify the GPU.
+        //     Somewhere in the Rubin timeframe, boot0 will no longer have space to add new GPU IDs.
+
         let boot0 = regs::NV_PMC_BOOT_0::read(bar);
 
-        Spec::try_from(boot0)
+        if boot0.is_older_than_fermi() {
+            return Err(ENODEV);
+        }
+
+        Spec::try_from(regs::NV_PMC_BOOT_42::read(bar))
     }
 }
 
-impl TryFrom<regs::NV_PMC_BOOT_0> for Spec {
+impl TryFrom<regs::NV_PMC_BOOT_42> for Spec {
     type Error = Error;
 
-    fn try_from(boot0: regs::NV_PMC_BOOT_0) -> Result<Self> {
+    fn try_from(boot42: regs::NV_PMC_BOOT_42) -> Result<Self> {
         Ok(Self {
-            chipset: boot0.chipset()?,
-            revision: boot0.into(),
+            chipset: boot42.chipset()?,
+            revision: boot42.into(),
         })
     }
 }
diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
index 274e53a1a44d..c6e2e08c754b 100644
--- a/drivers/gpu/nova-core/regs.rs
+++ b/drivers/gpu/nova-core/regs.rs
@@ -40,13 +40,24 @@
 });
 
 impl NV_PMC_BOOT_0 {
-    /// Combines `architecture_0` and `architecture_1` to obtain the architecture of the chip.
-    pub(crate) fn architecture(self) -> Result<Architecture> {
-        Architecture::try_from(
-            self.architecture_0() | (self.architecture_1() << Self::ARCHITECTURE_0_RANGE.len()),
-        )
+    pub(crate) fn is_older_than_fermi(self) -> bool {
+        // From https://github.com/NVIDIA/open-gpu-doc/tree/master/manuals :
+        const NV_PMC_BOOT_0_ARCHITECTURE_GF100: u8 = 0xc;
+
+        // Older chips left arch1 zeroed out. That, combined with an arch0 value that is less than
+        // GF100, means "older than Fermi".
+        self.architecture_1() == 0 && self.architecture_0() < NV_PMC_BOOT_0_ARCHITECTURE_GF100
     }
+}
+
+register!(NV_PMC_BOOT_42 @ 0x00000a00, "Extended architecture information" {
+    15:12   minor_revision as u8, "Minor revision of the chip";
+    19:16   major_revision as u8, "Major revision of the chip";
+    23:20   implementation as u8, "Implementation version of the architecture";
+    29:24   architecture as u8 ?=> Architecture, "Architecture value";
+});
 
+impl NV_PMC_BOOT_42 {
     /// Combines `architecture` and `implementation` to obtain a code unique to the chipset.
     pub(crate) fn chipset(self) -> Result<Chipset> {
         self.architecture()
-- 
2.51.2

[PATCH v9 4/4] gpu: nova-core: provide a clear error report for unsupported GPUs

[John Hubbard]

Pass in a PCI device to Spec::new(), and provide a Display
implementation for boot42, in order to provide a clear, concise report
of what happened: the driver read NV_PMC_BOOT42, and found that the GPU
is not supported.

For very old GPUs (older than Fermi), the driver still returns ENOTSUPP,
but it does so without a driver-specific dmesg report. That is exactly
appropriate, because if such a GPU is installed, it can only be
supported by Nouveau. And if so, the user is not helped by additional
error messages from Nova.

Here's the full dmesg output for a Blackwell (not yet supported) GPU:

NovaCore 0000:01:00.0: Probe Nova Core GPU driver.
NovaCore 0000:01:00.0: Unsupported chipset: boot42 = 0x1b2a1000 (architecture 0x1b, implementation 0x2)
NovaCore 0000:01:00.0: probe with driver NovaCore failed with error -524

Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Timur Tabi <ttabi@nvidia.com>
Cc: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/gpu/nova-core/gpu.rs  |  9 ++++++---
 drivers/gpu/nova-core/regs.rs | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 8e04628ca3d9..2bbc084e2095 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -191,7 +191,7 @@ pub(crate) struct Spec {
 }
 
 impl Spec {
-    fn new(bar: &Bar0) -> Result<Spec> {
+    fn new(dev: &device::Device, bar: &Bar0) -> Result<Spec> {
         // Some brief notes about boot0 and boot42, in chronological order:
         //
         // NV04 through NV50:
@@ -216,7 +216,10 @@ fn new(bar: &Bar0) -> Result<Spec> {
             return Err(ENODEV);
         }
 
-        Spec::try_from(regs::NV_PMC_BOOT_42::read(bar))
+        let boot42 = regs::NV_PMC_BOOT_42::read(bar);
+        Spec::try_from(boot42).inspect_err(|_| {
+            dev_err!(dev, "Unsupported chipset: {}\n", boot42);
+        })
     }
 }
 
@@ -268,7 +271,7 @@ pub(crate) fn new<'a>(
         bar: &'a Bar0,
     ) -> impl PinInit<Self, Error> + 'a {
         try_pin_init!(Self {
-            spec: Spec::new(bar).inspect(|spec| {
+            spec: Spec::new(pdev.as_ref(), bar).inspect(|spec| {
                 dev_info!(pdev.as_ref(),"NVIDIA ({})\n", spec);
             })?,
 
diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
index c6e2e08c754b..a53b013f2eca 100644
--- a/drivers/gpu/nova-core/regs.rs
+++ b/drivers/gpu/nova-core/regs.rs
@@ -67,6 +67,24 @@ pub(crate) fn chipset(self) -> Result<Chipset> {
             })
             .and_then(Chipset::try_from)
     }
+
+    /// Returns the raw architecture value from the register.
+    fn architecture_raw(self) -> u8 {
+        ((self.0 >> Self::ARCHITECTURE_RANGE.start()) & ((1 << Self::ARCHITECTURE_RANGE.len()) - 1))
+            as u8
+    }
+}
+
+impl kernel::fmt::Display for NV_PMC_BOOT_42 {
+    fn fmt(&self, f: &mut kernel::fmt::Formatter<'_>) -> kernel::fmt::Result {
+        write!(
+            f,
+            "boot42 = 0x{:08x} (architecture 0x{:x}, implementation 0x{:x})",
+            self.0,
+            self.architecture_raw(),
+            self.implementation()
+        )
+    }
 }
 
 // PBUS
-- 
2.51.2

Re: [PATCH v9 4/4] gpu: nova-core: provide a clear error report for unsupported GPUs

[John Hubbard]

On 11/14/25 5:09 PM, John Hubbard wrote:
> Pass in a PCI device to Spec::new(), and provide a Display
> implementation for boot42, in order to provide a clear, concise report
> of what happened: the driver read NV_PMC_BOOT42, and found that the GPU
> is not supported.
> 
> For very old GPUs (older than Fermi), the driver still returns ENOTSUPP,

ENODEV, actually, now.


thanks,
-- 
John Hubbard

> but it does so without a driver-specific dmesg report. That is exactly
> appropriate, because if such a GPU is installed, it can only be
> supported by Nouveau. And if so, the user is not helped by additional
> error messages from Nova.
> 
> Here's the full dmesg output for a Blackwell (not yet supported) GPU:
> 
> NovaCore 0000:01:00.0: Probe Nova Core GPU driver.
> NovaCore 0000:01:00.0: Unsupported chipset: boot42 = 0x1b2a1000 (architecture 0x1b, implementation 0x2)
> NovaCore 0000:01:00.0: probe with driver NovaCore failed with error -524
> 
> Cc: Alexandre Courbot <acourbot@nvidia.com>
> Cc: Danilo Krummrich <dakr@kernel.org>
> Cc: Timur Tabi <ttabi@nvidia.com>
> Cc: Joel Fernandes <joelagnelf@nvidia.com>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
>  drivers/gpu/nova-core/gpu.rs  |  9 ++++++---
>  drivers/gpu/nova-core/regs.rs | 18 ++++++++++++++++++
>  2 files changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
> index 8e04628ca3d9..2bbc084e2095 100644
> --- a/drivers/gpu/nova-core/gpu.rs
> +++ b/drivers/gpu/nova-core/gpu.rs
> @@ -191,7 +191,7 @@ pub(crate) struct Spec {
>  }
>  
>  impl Spec {
> -    fn new(bar: &Bar0) -> Result<Spec> {
> +    fn new(dev: &device::Device, bar: &Bar0) -> Result<Spec> {
>          // Some brief notes about boot0 and boot42, in chronological order:
>          //
>          // NV04 through NV50:
> @@ -216,7 +216,10 @@ fn new(bar: &Bar0) -> Result<Spec> {
>              return Err(ENODEV);
>          }
>  
> -        Spec::try_from(regs::NV_PMC_BOOT_42::read(bar))
> +        let boot42 = regs::NV_PMC_BOOT_42::read(bar);
> +        Spec::try_from(boot42).inspect_err(|_| {
> +            dev_err!(dev, "Unsupported chipset: {}\n", boot42);
> +        })
>      }
>  }
>  
> @@ -268,7 +271,7 @@ pub(crate) fn new<'a>(
>          bar: &'a Bar0,
>      ) -> impl PinInit<Self, Error> + 'a {
>          try_pin_init!(Self {
> -            spec: Spec::new(bar).inspect(|spec| {
> +            spec: Spec::new(pdev.as_ref(), bar).inspect(|spec| {
>                  dev_info!(pdev.as_ref(),"NVIDIA ({})\n", spec);
>              })?,
>  
> diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
> index c6e2e08c754b..a53b013f2eca 100644
> --- a/drivers/gpu/nova-core/regs.rs
> +++ b/drivers/gpu/nova-core/regs.rs
> @@ -67,6 +67,24 @@ pub(crate) fn chipset(self) -> Result<Chipset> {
>              })
>              .and_then(Chipset::try_from)
>      }
> +
> +    /// Returns the raw architecture value from the register.
> +    fn architecture_raw(self) -> u8 {
> +        ((self.0 >> Self::ARCHITECTURE_RANGE.start()) & ((1 << Self::ARCHITECTURE_RANGE.len()) - 1))
> +            as u8
> +    }
> +}
> +
> +impl kernel::fmt::Display for NV_PMC_BOOT_42 {
> +    fn fmt(&self, f: &mut kernel::fmt::Formatter<'_>) -> kernel::fmt::Result {
> +        write!(
> +            f,
> +            "boot42 = 0x{:08x} (architecture 0x{:x}, implementation 0x{:x})",
> +            self.0,
> +            self.architecture_raw(),
> +            self.implementation()
> +        )
> +    }
>  }
>  
>  // PBUS

Re: [PATCH v9 3/4] gpu: nova-core: add boot42 support for next-gen GPUs

[Alexandre Courbot]

On Sat Nov 15, 2025 at 10:09 AM JST, John Hubbard wrote:
> NVIDIA GPUs are moving away from using NV_PMC_BOOT_0 to contain
> architecture and revision details, and will instead use NV_PMC_BOOT_42
> in the future. NV_PMC_BOOT_0 will contain a specific set of values
> that will mean "go read NV_PMC_BOOT_42 instead".
>
> Change the selection logic in Nova so that it will claim Turing and
> later GPUs. This will work for the foreseeable future, without any
> further code changes here, because all NVIDIA GPUs are considered, from
> the oldest supported on Linux (NV04), through the future GPUs.
>
> Add some comment documentation to explain, chronologically, how boot0
> and boot42 change with the GPU eras, and how that affects the selection
> logic.
>
> Cc: Alexandre Courbot <acourbot@nvidia.com>
> Cc: Danilo Krummrich <dakr@kernel.org>
> Cc: Timur Tabi <ttabi@nvidia.com>
> Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
>  drivers/gpu/nova-core/gpu.rs  | 41 ++++++++++++++++++++++++++++++-----
>  drivers/gpu/nova-core/regs.rs | 21 +++++++++++++-----
>  2 files changed, 52 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
> index 88a6d7af9f37..8e04628ca3d9 100644
> --- a/drivers/gpu/nova-core/gpu.rs
> +++ b/drivers/gpu/nova-core/gpu.rs
> @@ -169,6 +169,15 @@ fn from(boot0: regs::NV_PMC_BOOT_0) -> Self {
>      }
>  }
>  
> +impl From<regs::NV_PMC_BOOT_42> for Revision {
> +    fn from(boot0: regs::NV_PMC_BOOT_42) -> Self {
> +        Self {
> +            major: boot0.major_revision(),
> +            minor: boot0.minor_revision(),
> +        }
> +    }
> +}

Just one nit: similarly to how we are converting the `TryFrom<BOOT_0>
for Spec` into a `TryFrom<BOOT_42>`, I think we don't need to keep
`From<BOOT_0> for Revision`. Actually we don't even want it, as using it
would mean we are relying on BOOT_0 instead of BOOT_42, which this
patchset nicely makes our only source of truth.

I'll thus remove the `From<BOOT_0>` implementation before applying.

Re: [PATCH v9 4/4] gpu: nova-core: provide a clear error report for unsupported GPUs

[Alexandre Courbot]

On Sat Nov 15, 2025 at 10:12 AM JST, John Hubbard wrote:
> On 11/14/25 5:09 PM, John Hubbard wrote:
>> Pass in a PCI device to Spec::new(), and provide a Display
>> implementation for boot42, in order to provide a clear, concise report
>> of what happened: the driver read NV_PMC_BOOT42, and found that the GPU
>> is not supported.
>> 
>> For very old GPUs (older than Fermi), the driver still returns ENOTSUPP,
>
> ENODEV, actually, now.

Fixed before applying - I was wondering actually, so the clarification
is welcome. :)

Re: [PATCH v9 0/4] gpu: nova: add boot42 support for next-gen GPUs

[Alexandre Courbot]

On Sat Nov 15, 2025 at 10:09 AM JST, John Hubbard wrote:
> Changes in v9:
>
> 1) Simplified the Revision updates, so that Revision's member fields can
>    remain private (thanks to Alex Courbot).
>
> 2) Restore a missing documentation comment line for chipset().
>
> 3) Removed the patch that changed from ENODEV to ENOTSUPP, and used
>    ENODEV to mean "GPU is not supported", because the driver core
>    expects that specific error code.
>
> 4) Rebased onto drm-rust-next, which already has patch 1/1 from v8, so
>    that one no longer appears in v9.

Pushed to drm-rust-next, thank you!

Re: [PATCH v9 3/4] gpu: nova-core: add boot42 support for next-gen GPUs

[John Hubbard]

On 11/15/25 6:13 AM, Alexandre Courbot wrote:
...
>> +impl From<regs::NV_PMC_BOOT_42> for Revision {
>> +    fn from(boot0: regs::NV_PMC_BOOT_42) -> Self {
>> +        Self {
>> +            major: boot0.major_revision(),
>> +            minor: boot0.minor_revision(),
>> +        }
>> +    }
>> +}
> 
> Just one nit: similarly to how we are converting the `TryFrom<BOOT_0>
> for Spec` into a `TryFrom<BOOT_42>`, I think we don't need to keep
> `From<BOOT_0> for Revision`. Actually we don't even want it, as using it
> would mean we are relying on BOOT_0 instead of BOOT_42, which this
> patchset nicely makes our only source of truth.
> 
> I'll thus remove the `From<BOOT_0>` implementation before applying.
> 

Yes, leaving it in was an oversight, good catch.

thanks,
-- 
John Hubbard