Re: [PATCH 1/8] rust: firmware: add request_into_buf()

[Timur Tabi <ttabi@nvidia.com>]

On Wed, 2026-06-10 at 19:03 +0100, Gary Guo wrote:
> > +pub fn request_into_buf(name: &CStr, dev: &Device, buf: &mut [u8]) -> Result<usize> {
> 
> It looks like this API design is very prone to misuse. Patch 5 of this series
> for example does not check for the returned size.

I was debating changing it to use request_partial_firmware_into_buf, which would "encourage" users
to verify the return value.

> Also, I think people might just write `buf[..size]` and then it'll panic because
> `size` can be larger.

Why would it panic if the buffer is larger than the size of the file?  The kernel API requires you
to know the size of the file before using request_firmware_into_buf(). If the file on disk is larger
than the buffer, the kernel returns -EFBIG.  If the file on this is smaller, then it is loader
completely and the returned Result<usize> is the number of bytes actually loaded from disk.

This has always been a problem for Nouveau because the GSP binary is 90MB in size, and
request_firmware() allocates a contiguous block of memory for it, only for us to memcpy it to a
vmalloc'd buffer.

So now, thanks to TLVs, we can finally use request_firmware_into_buf() for gsp.bin.