sys/dev/mpr/mpr_user.c
272 ↗	(On Diff #187256)	silly question. If there's no driver attached, then how do we open a device to all this ioctl? How could you possibly recover a device that mpr doesn't attach to? Why do you need that code to allocate resources? You might want to explain the exact mechanism how this comes to pass. the missing bit from the comments is that that mpr associate with the device because probe succeeds. But the bigger issue, I'd think, is that if probe succeeds and attach doesn't, then I think there'd be no devsw registered...

sys/dev/mpr/mpr_user.c
272 ↗	(On Diff #187256)	Indeed, probe succeeds, and mpr_attach() fails, because the device stays in the MPI2_IOC_STATE_RESET state, because it has no firmware. So we end up with no /dev/mprN device. So, this patch adds a new /dev/mpr_hostboot device, that isn't associated with any hardware, and will just "always exist". Then `mprutil` can IOCTL to it, and ask it "could you please boot pci0:7:0:0 with this firmware (pointer + length)" And then you can `devctl attach pci0:7:0:0` and suddenly you have /dev/mpr0 that you didn't before. The primary use case is actually to preload the firmware in loader.conf and stop the initial attach from failing, be having the card booted to said firmware so it doesn't fail to attach. This is some oddball hardware I bought, a single card that is a PCI-e switch, a Mellanox ConnectX-3, and 2x LSI SAS2308 chips (basically 9305-8e), all on one card. When making this custom card, they did not include any flash storage for the firmware. see: https://forums.servethehome.com/index.php?threads/unique-oem-dual-lsi-2308-mellanox-connectx-3-vpi-combo-expansion-cards.30532/ If you'd like one to play with, they are only $29.99: https://www.ebay.com/itm/188115617273?itmmeta=01M2V5GZ247M7TP012W8M9FMF2&hash=item2bcc9085f9:g:YPcAAOSwpI5eCaDK