On Fri Oct 17, 2025 at 10:15 AM JST, Alistair Popple wrote: > On 2025-10-17 at 11:43 +1100, Alexandre Courbot <[email protected]> wrote... >> On Fri Oct 17, 2025 at 8:11 AM JST, Danilo Krummrich wrote: >> > On Fri Oct 17, 2025 at 1:03 AM CEST, Alistair Popple wrote: >> >> On 2025-10-16 at 17:23 +1100, Alexandre Courbot <[email protected]> >> >> wrote... >> >>> On Mon Oct 13, 2025 at 3:20 PM JST, Alistair Popple wrote: >> >>> > +impl GspFwWprMeta { >> >>> > + pub(crate) fn new(gsp_firmware: &GspFirmware, fb_layout: >> >>> > &FbLayout) -> Self { >> >>> > + Self(bindings::GspFwWprMeta { >> >>> > + magic: r570_144::GSP_FW_WPR_META_MAGIC as u64, >> >>> > + revision: u64::from(r570_144::GSP_FW_WPR_META_REVISION), >> >>> > + sysmemAddrOfRadix3Elf: gsp_firmware.radix3_dma_handle(), >> >>> > + sizeOfRadix3Elf: gsp_firmware.size as u64, >> >>> >> >>> Very unfortunately I'm afraid we will need to replace the `as` in this >> >>> method with `u64::try_from` and make it return a `Result` for now. >> >> >> >> And presumably most of the other `as` keywords in this function dealing >> >> with >> >> usize as well? Have made the change but would you mind quickly explaining >> >> why this is needed? Is the concern that usize might be more than 64 bits >> >> or >> >> something? >> >> Indeed, the concern is that `as` performs a lossy conversion without >> warning, which could catch us off-guard if e.g. some type changes in the >> bindings. >> >> > >> > Since nova-core depends on CONFIG_64BIT, I think we want a helper function >> > that >> > converts usize to u64 infallibly. >> > >> > This helper function can simply generate a compile time error, when >> > !CONFIG_64BIT, etc. >> > >> > We can do this locally in nova-core, but it could also find it's place in >> > the >> > generic infrastructure. nova-core clearly won't be the last driver running >> > into >> > this inconvinience. >> >> That would definitely be the correct way to address this. > > Sure. Although I don't really have a problem with the binding constructors > being > fallible as plenty of the others are anyway.
I think we can address the non-fallible conversions as a separate task (as there are many sites that could be similarly optimized in the nova-core code), so fallible constructors are acceptable imho.
