ECE 441 · Week 7
Modern Computer: Secure Infrastructure
One kernel revision moves on spare media.
Week 7 of 10 · Solitude
ECE 441 · Week 7 · In class
One kernel revision moves on spare media.
- Record boot, the device tree, and one peripheral.
- The spare on this section is a card.
- Leave the main card alone until the move is on the spare.
- The version string is one of the two the instructor writes on the board.
ECE 441 · Week 7 · In class
One kernel revision moves on spare media. (continued)
- Copy the one you will install, before you install it.
- That string is the homework.
- These notes do not print version strings.
ECE 441 · Week 7 · In class
Boot the previous revision once more so you can name which one you left installed.
- The record is what the board still does after the move: boot, the device tree, and one peripheral.
ECE 441 · Week 7 · Lecture
A kernel move is an experiment
- One thing changes: the kernel revision. The card, the board, and the bootloader stay.
- Record what the board does before the move, then the same things after.
- Three records: does it boot, what device tree does it run, does one peripheral work.
- It happens on the spare card; the main card is untouched until the move is on the spare.
ECE 441 · Week 7 · Lecture
Before and after, the same commands
uname -r
cat /proc/cmdline
dtc -q -s -I fs -O dts -o tree-$(uname -r).dts \
/proc/device-tree
dmesg | grep -i '<driver>'
ls /sys/bus/<bus>/devices/- Naming the tree file after
uname -rkeeps the two records apart. - Run the identical list on both kernels: a different command is a different experiment.
ECE 441 · Week 7 · Lecture
What can change when the kernel moves
| Record | What to look for |
|---|---|
| Boot | Same end event reached? New warnings or errors? |
| Device tree | A new tree shipped with the kernel, or the same one |
| Peripheral | Driver binds, device appears, one transaction succeeds |
A peripheral that still works is a result worth recording, not a blank row.
ECE 441 · Week 7 · Lecture
Knowing which kernel you left installed
uname -rnames the kernel running, not every kernel on the card.ls /bootshows which kernel and device-tree files the card holds.- Boot the previous revision once more, so the record says which one stays installed.
ECE 441 · Week 7 · Lab
Lab
- Move one kernel revision on spare media.
- Record what the board still does: boot, the device tree, and one peripheral. Second pass: boot the previous revision once more so you can name which one you left installed.
- Assemble the lab hand-in: A record of one kernel revision move: what the board still does.
ECE 441 · Week 7 · Lab
Hand in
A record of one kernel revision move: what the board still does.
ECE 441 · Week 7 · Homework
Homework
- Write the kernel package version you will move to, from the lecture list, before you install it.
ECE 441 · Week 7 · Homework
Turn in
That version string.
ECE 441 · Week 7 · Read
Read
On the lab site: Module 12, A whole system, does not grade a kernel-revision move. This week is past Module 12.
ECE 441 · Week 7 · Next
Week 8
From the public reset description, say what the first stage can check at reset and what it cannot.