Re: [PATCH 05/13] gpu: nova-core: gsp: keep FMC boot params DMA region alive during error

["Gary Guo" <gary@garyguo.net>]

On Wed Jun 17, 2026 at 6:27 AM BST, Eliot Courtney wrote:
> On Tue Jun 16, 2026 at 2:23 AM JST, Gary Guo wrote:
>> On Mon Jun 15, 2026 at 3:40 PM BST, Eliot Courtney wrote:
>>> Currently, if, for example `boot_fmc` fails, `FmcBootArgs` will be
>>> dropped before the boot unload guard. But until everything is unloaded,
>>> GSP may access this memory, so make sure it doesn't get deallocated.
>>
>> Hmm, this looks very weirld. `boot_fmc` only needs `&args` but it actually need
>> it for much longer?
>>
>> This is hinting to me that the signature is wrong of the `boot_fmc` function is
>> wrong..
>>
>> What is the exact lifetime requirement for GSP?
>
> Once `wait_for_gsp_lockdown_release` returns, it no longer needs the
> allocation. In the case that we get an error in this function, GSP may
> be (asychronously to the CPU) accessing the DMA memory we gave it. So
> FmcBootArgs should stay alive until FspUnloadBundle finishes (GSP is
> reset) if there is an error, or, until `wait_for_gsp_lockdown_release`
> returns successfully.
>
> So for `boot_fmc` to cover the actual lifetime it would need to be
> responsible for waiting until GSP is reset, which it doesn't feel like
> it should be responsible for (even as some unload bundle that it
> returns).

I suppose logically the GSP does need to take ownership of the full `Coherent`
until unload if this errors?

Best,
Gary