Re: [13/16] gpu: nova-core: Add support for VBIOS ucode extraction for boot

Joel Fernandes
2025-04-25T17:10:07Z

On April 25, 2025, 2:32 a.m. UTC Joel Fernandes wrote:
> Hello, Danilo,
>
> On April 24, 2025, 8:17 p.m. UTC Danilo Krummrich wrote:
> > On Thu, Apr 24, 2025 at 03:54:48PM -0400, Joel Fernandes wrote:
> > > On Wed, Apr 23, 2025 at 05:02:58PM +0200, Danilo Krummrich wrote:
> > > > On Wed, Apr 23, 2025 at 10:52:42AM -0400, Joel Fernandes wrote:
> > > > > Hello, Danilo,
> > > > > Thanks for all the feedback. Due to the volume of feedback, I will respond
> > > > > incrementally in multiple emails so we can discuss as we go - hope that's Ok but
> > > > > let me know if that is annoying.
> > > >
> > > > That's perfectly fine, whatever works best for you. :)
> > > >
> > > > > On 4/23/2025 10:06 AM, Danilo Krummrich wrote:
> > > > >
> > > > > >> +impl Vbios {
> > > > > >> + /// Read bytes from the ROM at the current end of the data vector
> > > > > >> + fn read_more(bar0: &Devres<Bar0>, data: &mut KVec<u8>, len: usize) -> Result {
> > > > > >> + let current_len = data.len();
> > > > > >> + let start = ROM_OFFSET + current_len;
> > > > > >> +
> > > > > >> + // Ensure length is a multiple of 4 for 32-bit reads
> > > > > >> + if len % core::mem::size_of::<u32>() != 0 {
> > > > > >> + pr_err!("VBIOS read length {} is not a multiple of 4\n", len);
> > > > > >
> > > > > > Please don't use any of the pr_*() print macros within a driver, use the dev_*()
> > > > > > ones instead.
> > > > >
> > > > > Ok I'll switch to this. One slight complication is I've to retrieve the 'dev'
> > > > > from the Bar0 and pass that along, but that should be doable.
> > > >
> > > > You can also pass the pci::Device reference to VBios::probe() directly.
> > >
> > >
> > > This turns out to be rather difficult to do in the whole vbios.rs because
> > > we'd have to them propogate pdev to various class methods which may print
> > > errors
> >
> > Note that you can always create an ARef<pci::Device> instance from a
> > &pci::Device, which you can store temporarily if needed. Though I don't think
> > it's needed here.
> >
> > > (some of which don't make sense to pass pdev to, like try_from()).
> >
> > Yeah, it's indeed difficult with a TryFrom or From impl. I guess you're
> > referring to things like
> >
> > impl TryFrom<&[u8]> for PcirStruct
> >
> > and I actually think that's a bit of an abuse of the TryFrom trait. A &[u8]
> > isn't really something that is "natural" to convert to a PcirStruct.
> >
> > Instead you should just move this code into a normal constructor, i.e.
> > PcirStruct::new(). Here you can then also pass a device reference to print
> > errors.
>
> Ok, I had a similar feeling about excessive TryFrom. I will
> make this change.
>
> >
> > We should really stick to dev_*() print macros from within driver code.
> >
>
> Ack.

Here are the changes: https://bit.ly/4lOHk4s

It looks better for sure :)

Now onto working on the loop { } and the read_..() method suggestions. :)

- Joel