bootlinux: add bisection support

This adds automatic bisection support first through the CLI by
using simple command line options. The first target goal to test
is very simple, check if the kernel boots or not. There is no need
for a custom workflow for this. We just enable the user to set the
values through the command line interface like this:

git clone git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git \
  --reference /mirror/linux-next.git linux
make defconfig-bisection \
	GOOD=v6.15-rc2 \
	BAD=next-20250422 \
	KDEVOPS_HOSTS_PREFIX="bisect" \
	LINUX_TREE="git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git" -j128
make -j128
make bringup
make linux # Boots to good at first
make linux-bisection # Runs the bisection script

For now confine this feature to BOOTLINUX_9P as its not clear what to do
about terraform yet. We can add that support later.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

Author: mcgrof

defconfigs/bisection

@@ -0,0 +1,9 @@
+CONFIG_GUESTFS=y
+CONFIG_LIBVIRT=y
+
+CONFIG_WORKFLOW_LINUX_CUSTOM=y
+CONFIG_BOOTLINUX=y
+CONFIG_BOOTLINUX_9P=y
+CONFIG_BOOTLINUX_BISECT_ENABLE=y
+
+CONFIG_DEVCONFIG_ENABLE_SYSTEMD_JOURNAL_REMOTE=y

playbooks/roles/bootlinux/defaults/main.yml

@@ -52,3 +52,9 @@ kdevops_workflow_enable_cxl: False
 
 bootlinux_cxl_test: False
 bootlinux_tree_set_by_cli: False
+bootlinux_bisect_enable: False
+bootlinux_bisect_enable_cli: False
+bootlinux_bisect_ref_good_cli: False
+bootlinux_bisect_ref_bad_cli: False
+bootlinux_bisect_script_boot: False
+bootlinux_bisect_script_custom: False

playbooks/roles/bootlinux/tasks/main.yml

@@ -650,3 +650,48 @@
   vars:
     running_kernel: "{{ uname_cmd.stdout_lines.0 }}"
   tags: [ 'linux', 'git', 'config', 'uname' ]
+
+- name: Copy git bisection script over
+  template:
+    src: "{{ bootlinux_bisect_script }}.j2"
+    dest: "{{ bootlinux_9p_host_path }}/{{ bootlinux_bisect_script }}"
+    mode: 0644
+  tags: [ 'bisect' ]
+  when:
+    - bootlinux_bisect_enable|bool
+  run_once: true
+  delegate_to: localhost
+
+- name: Set up bisection for git
+  command: "git bisect start {{ bootlinux_bisect_ref_bad }} {{ bootlinux_bisect_ref_good }}"
+  register: build
+  changed_when: "build.rc == 0"
+  args:
+    chdir: "{{ bootlinux_9p_host_path }}"
+  tags: [ 'bisect' ]
+  when:
+    - bootlinux_bisect_enable|bool
+  run_once: true
+  delegate_to: localhost
+
+- name: Ensure bisection script is executable
+  file:
+    path: "{{ bootlinux_9p_host_path }}/{{ bootlinux_bisect_script }}"
+    mode: '0755'
+    state: file
+  when: bootlinux_bisect_enable | bool
+  delegate_to: localhost
+  run_once: true
+  tags: [ 'bisect' ]
+
+- name: Run the the bisection script
+  command: "git bisect run {{ bootlinux_9p_host_path }}/{{ bootlinux_bisect_script }}"
+  register: build
+  changed_when: "build.rc == 0"
+  args:
+    chdir: "{{ bootlinux_9p_host_path }}"
+  tags: [ 'bisect' ]
+  when:
+    - bootlinux_bisect_enable|bool
+  run_once: true
+  delegate_to: localhost

playbooks/roles/bootlinux/templates/bisect-boot.sh.j2

@@ -0,0 +1,7 @@
+#!/bin/bash
+# SPDX-License-Identifier: copyleft-next-0.3.1
+#
+# If make linux-deploy fails for reasons unrelated to the bug we're tracking
+# (e.g., a build error) we bail with exit code 125 to allow git to skip that
+# commit.
+make linux-deploy || exit 125

workflows/linux/Kconfig

@@ -10,6 +10,21 @@ config BOOTLINUX_TREE_REF_SET_BY_CLI
 	output yaml
 	default $(shell, scripts/check-cli-set-var.sh LINUX_TREE_REF)
 
+config BOOTLINUX_BISECT_ENABLE_CLI
+	bool
+	output yaml
+	default $(shell, scripts/check-cli-set-var.sh LINUX_BISECT)
+
+config BOOTLINUX_BISECT_REF_GOOD_CLI
+	bool
+	output yaml
+	default $(shell, scripts/check-cli-set-var.sh GOOD)
+
+config BOOTLINUX_BISECT_REF_BAD_CLI
+	bool
+	output yaml
+	default $(shell, scripts/check-cli-set-var.sh BAD)
+
 config BOOTLINUX_HAS_PURE_IOMAP_CONFIG
 	bool
 
@@ -173,7 +188,8 @@ config BOOTLINUX_TREE_CUSTOM_URL
 
 config BOOTLINUX_TREE_CUSTOM_REF
 	string "Custom Linux kernel tag or branch to use"
-	default $(shell, ./scripts/append-makefile-vars.sh $(LINUX_TREE_REF)) if BOOTLINUX_TREE_REF_SET_BY_CLI
+	default $(shell, ./scripts/append-makefile-vars.sh $(GOOD)) if BOOTLINUX_BISECT_REF_GOOD_CLI && !BOOTLINUX_TREE_REF_SET_BY_CLI
+	default $(shell, ./scripts/append-makefile-vars.sh $(LINUX_TREE_REF)) if BOOTLINUX_TREE_REF_SET_BY_CLI && !BOOTLINUX_BISECT_REF_GOOD_CLI
 	default "master" if !BOOTLINUX_TREE_REF_SET_BY_CLI
 	help
 	  The git ID or branch name to check out to compile linux.
@@ -278,9 +294,71 @@ config BOOTLINUX_TREE_LOCALVERSION
 	help
 	  The Linux local version to use (for uname).
 
+config BOOTLINUX_BISECT_ENABLE
+	bool "Do you want to bisect a broken kernel?"
+	default y
+	depends on BOOTLINUX_9P
+	output yaml
+	help
+	  Do you need to automate bisecting some broken kernel?
+
+if BOOTLINUX_BISECT_ENABLE
+
+choice
+	prompt "Bisection script to use"
+	default BOOTLINUX_BISECT_SCRIPT_BOOT
+
+config BOOTLINUX_BISECT_SCRIPT_BOOT
+	bool "Ensures we can at least boot"
+	help
+	  This helps ensure we can at laest boot into the host. That's it.
+
+config BOOTLINUX_BISECT_SCRIPT_CUSTOM
+	bool "You will provide your own bisection script"
+	help
+	  If you to test a new bisection script you can use this.
+
+endchoice
+
+config BOOTLINUX_BISECT_SCRIPT_CUSTOM_PATH
+	string "Custom path to git bisection script to use"
+	depends on BOOTLINUX_BISECT_SCRIPT_CUSTOM
+	default ""
+	output yaml
+	help
+	  The custom path to the bisect script we will use. Instead of building
+	  the kernel and booting it, 'make linux' will do the bisection
+	  automatically for you based on the script.
+
+config BOOTLINUX_BISECT_SCRIPT
+	string
+	output yaml
+	default "bisect-boot.sh" if BOOTLINUX_BISECT_SCRIPT_BOOT
+	default BOOTLINUX_BISECT_SCRIPT_CUSTOM_PATH if BOOTLINUX_BISECT_SCRIPT_BOOT
+
+
+config BOOTLINUX_BISECT_REF_GOOD
+	string "The last known good commit"
+	default BOOTLINUX_TREE_REF if !BOOTLINUX_BISECT_REF_GOOD_CLI
+	default $(shell, ./scripts/append-makefile-vars.sh $(GOOD)) if BOOTLINUX_BISECT_REF_GOOD_CLI
+	output yaml
+	help
+	  The known kernel commit to be good.
+
+config BOOTLINUX_BISECT_REF_BAD
+	string "The known broken commit"
+	default BOOTLINUX_TREE_STABLE_REF if !BOOTLINUX_BISECT_REF_BAD_CLI
+	default $(shell, ./scripts/append-makefile-vars.sh $(BAD)) if BOOTLINUX_BISECT_REF_BAD_CLI
+	output yaml
+	help
+	  The first broken tag.
+
+endif # BOOTLINUX_BISECT_ENABLE
+
 config BOOTLINUX_SHALLOW_CLONE
 	bool "Shallow git clone"
 	default y
+	depends on !BOOTLINUX_BISECT_ENABLE
 	help
 	  If enabled the git tree cloned with be cloned using a shallow tree
 	  with history truncated. You want to enable this if you really don't

workflows/linux/Makefile

@@ -104,6 +104,13 @@ linux-mount:
 		--tags vars,9p_mount \
 		--extra-vars="$(BOOTLINUX_ARGS)" $(LIMIT_HOSTS)
 
+PHONY += linux-bisect
+linux-bisect:
+	$(Q)ansible-playbook $(ANSIBLE_VERBOSE) -i \
+		$(KDEVOPS_HOSTFILE) $(KDEVOPS_PLAYBOOKS_DIR)/bootlinux.yml \
+		--tags vars,bisect \
+		--extra-vars="$(BOOTLINUX_ARGS)" $(LIMIT_HOSTS)
+
 PHONY += linux-deploy
 linux-deploy:
 	$(Q)ansible-playbook $(ANSIBLE_VERBOSE) -i \
@@ -176,6 +183,14 @@ linux-help-cxl:
 LINUX_HELP_EXTRA += linux-help-cxl
 endif
 
+ifeq (y,$(CONFIG_BOOTLINUX_BISECTION))
+PHONY += linux-help-bisection
+linux-help-bisection:
+	@echo "linux-bisection    - Bisects the kernel automatically for you"
+
+LINUX_HELP_EXTRA += linux-help-bisection
+endif
+
 HELP_TARGETS+=linux-help-menu
 HELP_TARGETS+=$(LINUX_HELP_EXTRA)
 HELP_TARGETS+=linux-help-end