Re: [PATCH v3 5/6] gpu: nova-core: skip the IFR header if present

[John Hubbard <jhubbard@nvidia.com>]

On 4/15/26 5:26 PM, Timur Tabi wrote:
...
> +fn current_offset(dev: &device::Device, bar0: &Bar0) -> Result<usize> {
> +    let signature = bar0.read(ga100::NV_PBUS_IFR_FMT_FIXED0).signature();
> +
> +    if signature == NV_PBUS_IFR_FMT_FIXED0_SIGNATURE_VALUE {
> +        let fixed1 = bar0.read(ga100::NV_PBUS_IFR_FMT_FIXED1);
> +
> +        match fixed1.version() {
> +            // Note: We do not actually expect to see v1 or v2 on these GPUs

Then why even match for it? No need to "support" HW or FW that doesn't,
and won't ever exist, right?

thanks,
-- 
John Hubbard

> +            1 | 2 => {
> +                let fixed_data_size = usize::from(fixed1.fixed_data_size());
> +                let pmgr_rom_addr_offset = fixed_data_size + IFR_SW_EXT_ROM_ADDR_OFFSET;
> +                bar0.try_read32(ROM_OFFSET + pmgr_rom_addr_offset)
> +                    .map(|v| v as usize)
> +            }
> +            3 => {
> +                let fixed2 = bar0.read(ga100::NV_PBUS_IFR_FMT_FIXED2);
> +                let total_data_size = usize::from(fixed2.total_data_size());
> +                let dir_offset =
> +                    bar0.try_read32(ROM_OFFSET + total_data_size)? as usize + RFW_FLASH_STATUS_SIZE;
> +                let dir_sig = bar0.try_read32(ROM_OFFSET + dir_offset)?;
> +                if dir_sig != NV_ROM_DIRECTORY_IDENTIFIER {
> +                    dev_err!(dev, "could not find IFR ROM directory\n");
> +                    return Err(EINVAL);
> +                }
> +                bar0.try_read32(ROM_OFFSET + dir_offset + 8)
> +                    .map(|v| v as usize)
> +            }
> +            _ => {
> +                dev_err!(dev, "unsupported IFR header version {}\n", fixed1.version());
> +                Err(EINVAL)
> +            }
> +        }
> +    } else {
> +        Ok(0)
> +    }
> +}
> +
>  impl<'a> VbiosIterator<'a> {
>      fn new(dev: &'a device::Device, bar0: &'a Bar0) -> Result<Self> {
>          Ok(Self {
>              dev,
>              bar0,
>              data: KVec::new(),
> -            current_offset: 0,
> +            current_offset: current_offset(dev, bar0)?,
>              last_found: false,
>          })
>      }