On Mon, Nov 25, 2024 at 05:19:54PM +0100, Christian König wrote: > Am 25.11.24 um 16:29 schrieb Matthew Brost: > > On Fri, Nov 15, 2024 at 10:27:59AM -0800, Matthew Brost wrote: > > > [SNIP] > > > We use this interface to read a BO marked with a dumpable flag during a > > > GPU hang in our error capture code. This is an internal KMD feature, not > > > directly exposed to user space. Would adding this helper be acceptable > > > for this use case? I can add kernel indicating the current restrictions > > > of the helper (do not directly expose to user space) too if that would > > > help. > > > > > Christian - ping on above. > > Sorry, I will try to give those mailing list tasks a bit more time in before > the xmas holidays. > > That is an acceptable use case, but the problem is that this helper won't > work for that. > > See during a GPU hang you can't lock BOs, so how do you want to look into > their content with the peek helper? > Agree we cannot lock BO directly in GPU hang path (TDR). Our error capture code takes a snapshot of some the GPU state which is small and safe to capture in TDR and kicks a worker which opportunistically captures the VM state which has been marked to be captured. This is where the helper is called and it is safe to lock the BO. Matt > The only thing you could potentially do is to trylock the BO and then dump, > but that would most likely be a bit unreliable. > > Regards, > Christian. > > > > Matt