# Jonathan Kollasch
## [[!template id=man name="ddb" section="4"]] tips
### locating a softc
This locates a device's softc using it's `cfdriver_t` (e.g. `&mainbus_cd`, `&cpu_cd`) and its "device unit" (e.g. the `0` in `mainbus0`).
db{0}> call device_lookup_private(ohci_cd, 0)
0xffff800045fb2008
### locating structure members
This uses [[!template id=man name="gdb" section="1"]] and a kernel with debugging symbols to find the offset to a element in a structure.
$ gdb netbsd.gdb
...
(gdb) print &((struct ohci_softc *)0)->iot
$3 = (bus_space_tag_t *) 0x478
(gdb) print &((struct ohci_softc *)0)->ioh
$4 = (bus_space_handle_t *) 0x480
### peeking at mapped registers
db{0}> call bus_space_read_4(*(ffff800045fb2008+478), *(ffff800045fb2008+480), 0)
0x110
## Unfinished Projects
### x86 UEFI kernel loader
Needs more work and cleanup.
Work has been done using the OVMF BIOS images for Qemu.
### bcm47xx for evbmips
Boots multiuser on NFS root, needs more work and cleanup.
This project is on hold until there's a miniature userland that fits in 4-8MiB flash storage devices, on a flash-oriented file system.
[[!template id=man name="bce" section="4"]] and [[!template id=man name="bwi" section="4"]] would need refactoring to be bus-independent.
### Memory-mapped PCI config access on x86
Needs cleanup, and maybe some more validation of MCFG tables.
CVSweb for NetBSD wikisrc <wikimaster@NetBSD.org> software: FreeBSD-CVSweb