gem5: you can exit m5term with ~.

README.adoc

@@ -400,7 +400,7 @@ If you haven't built Buildroot yet for <<qemu-buildroot-setup>>, you can build f
 ./run --gem5
 ....
 
-`--no-qemu` is optional, but it makes the 
+`--no-qemu` is optional, but it makes the build slightly faster TODO: after first build:
 ....
 ./download-dependencies --gem5
 ./build-gem5 --gem5
@@ -416,7 +416,11 @@ To get a terminal, either open a new shell and run:
 ./gem5-shell
 ....
 
-The only way to exit the shell is to kill the gem5 on the previous shell
+You can quit the shell without killing gem5 by typing tilde followed by a period:
+
+....
+~.
+....
 
 If you are inside tmux, which I highly recommend, just run gem5 with:
 
@@ -3696,31 +3700,44 @@ By default, we use a `.config` that is a mixture of:
 * Buildroot's minimal per machine `.config`, which has the minimal options needed to boot
 * our <<kernel-configs-about,kernel configs>> which enables options we want to play with
 
-Use just your own exact `.config` instead:
+To modify a single option on top of our defaults, do:
 
 ....
-./build-buildroot -K data/myconfig -l
+./build-linux --kernel-config 'CONFIG_FORTIFY_SOURCE=y'
 ....
 
-Beware that Buildroot can `sed` override some of the configurations we make no matter what, e.g. it forces `CONFIG_BLK_DEV_INITRD=y` when `BR2_TARGET_ROOTFS_CPIO` is on, so you might want to double check as explained at <<find-the-kernel-config>>. TODO check if there is a way to prevent that patching and maybe patch Buildroot for it, it is too fuzzy. People should be able to just build with whatever `.config` they want.
-
-Modify a single option:
+Kernel modules depend on certain kernel configs, and therefore in general you might have to clean and rebuild the kernel modules after changing the kernel config:
 
 ....
-./build-buildroot -C 'CONFIG_FORTIFY_SOURCE=y' -l
+./build-modules --clean
+./build-modules
 ....
 
-Use an extra kernel config fragment file:
+and then proceed as in <<your-first-kernel-module-hack>>.
+
+You might often get way without rebuilding the kernel modules however.
+
+To use an extra kernel config fragment file on top of our defaults, do:
 
 ....
 printf '
 CONFIG_IKCONFIG=y
 CONFIG_IKCONFIG_PROC=y
-' > myconfig
-./build-buildroot -c 'myconfig' -l
+' > data/myconfig
+./build-buildroot --kernel-config-fragment 'data/myconfig'
 ....
 
-`-K`, `-c`, `-C` can all be used at the same time. Options passed via `-C` take precedence over `-c`, which takes precedence over `-K`.
+To use just your own exact `.config` instead of our defaults ones, use:
+
+....
+./build-linux --kernel-custom-config-file data/myconfig
+....
+
+The following options can all be used together, sorted by decreasing config setting power precedence:
+
+* `--kernel-config`
+* `--kernel-config-fragment`
+* `--kernel-custom-config-file`
 
 ==== Find the kernel config
 
@@ -3770,6 +3787,8 @@ although this can be useful when someone gives you a random image.
 
 TODO: explain link:update-buildroot-kernel-config[]
 
+TODO Beware that Buildroot can `sed` override some of the configurations we make no matter what, e.g. it forces `CONFIG_BLK_DEV_INITRD=y` when `BR2_TARGET_ROOTFS_CPIO` is on, so you might want to double check as explained at <<find-the-kernel-config>>. TODO check if there is a way to prevent that patching and maybe patch Buildroot for it, it is too fuzzy. People should be able to just build with whatever `.config` they want.
+
 We have managed to come up with minimalistic kernel configs that work for both QEMU and gem5 (oh, the hours of bisection).
 
 Our configs are all based on Buildroot's configs, which were designed for QEMU, and then on top of those we also add:
@@ -7608,7 +7627,8 @@ static void arm_sysctl_write(void *opaque, hwaddr offset,
 and then rebuild with:
 
 ....
-./build-buildroot --arch arm -c kernel_config_fragment/leds -lq
+./build-buildroot --arch arm -c kernel_config_fragment/leds -l
+./build-qemu --arch arm
 ....
 
 But beware that one of the LEDs has a heartbeat trigger by default (specified on dts), so it will produce a lot of output.