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https://github.com/cirosantilli/linux-kernel-module-cheat.git
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run: add qemu options directly into run
readme: add ascii tmux split screenshot to preamble
This commit is contained in:
Ciro Santilli
83
README.adoc
83
README.adoc
@@ -51,7 +51,49 @@ hello2 cleanup
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which are `printk` messages from `init` and `cleanup` methods of those modules.
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image:screenshot.png[image]
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Once you use <<gdb>> and <<tmux>>, your terminal will look a bit like this:
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....
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[ 1.451857] input: AT Translated Set 2 keyboard as /devices/platform/i8042/s1│loading @0xffffffffc0000000: ../kernel_module-1.0//timer.ko
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[ 1.454310] ledtrig-cpu: registered to indicate activity on CPUs │(gdb) b lkmc_timer_callback
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[ 1.455621] usbcore: registered new interface driver usbhid │Breakpoint 1 at 0xffffffffc0000000: file /home/ciro/bak/git/linux-kernel-module
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[ 1.455811] usbhid: USB HID core driver │-cheat/out/x86_64/buildroot/build/kernel_module-1.0/./timer.c, line 28.
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[ 1.462044] NET: Registered protocol family 10 │(gdb) c
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[ 1.467911] Segment Routing with IPv6 │Continuing.
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[ 1.468407] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver │
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[ 1.470859] NET: Registered protocol family 17 │Breakpoint 1, lkmc_timer_callback (data=0xffffffffc0002000 <mytimer>)
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[ 1.472017] 9pnet: Installing 9P2000 support │ at /home/ciro/bak/git/linux-kernel-module-cheat/out/x86_64/buildroot/build/
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[ 1.475461] sched_clock: Marking stable (1473574872, 0)->(1554017593, -80442)│kernel_module-1.0/./timer.c:28
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[ 1.479419] ALSA device list: │28 {
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[ 1.479567] No soundcards found. │(gdb) c
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[ 1.619187] ata2.00: ATAPI: QEMU DVD-ROM, 2.5+, max UDMA/100 │Continuing.
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[ 1.622954] ata2.00: configured for MWDMA2 │
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[ 1.644048] scsi 1:0:0:0: CD-ROM QEMU QEMU DVD-ROM 2.5+ P5│Breakpoint 1, lkmc_timer_callback (data=0xffffffffc0002000 <mytimer>)
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[ 1.741966] tsc: Refined TSC clocksource calibration: 2904.010 MHz │ at /home/ciro/bak/git/linux-kernel-module-cheat/out/x86_64/buildroot/build/
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[ 1.742796] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x29dc0f4s│kernel_module-1.0/./timer.c:28
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[ 1.743648] clocksource: Switched to clocksource tsc │28 {
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[ 2.072945] input: ImExPS/2 Generic Explorer Mouse as /devices/platform/i8043│(gdb) bt
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[ 2.078641] EXT4-fs (vda): couldn't mount as ext3 due to feature incompatibis│#0 lkmc_timer_callback (data=0xffffffffc0002000 <mytimer>)
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[ 2.080350] EXT4-fs (vda): mounting ext2 file system using the ext4 subsystem│ at /home/ciro/bak/git/linux-kernel-module-cheat/out/x86_64/buildroot/build/
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[ 2.088978] EXT4-fs (vda): mounted filesystem without journal. Opts: (null) │kernel_module-1.0/./timer.c:28
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[ 2.089872] VFS: Mounted root (ext2 filesystem) readonly on device 254:0. │#1 0xffffffff810ab494 in call_timer_fn (timer=0xffffffffc0002000 <mytimer>,
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[ 2.097168] devtmpfs: mounted │ fn=0xffffffffc0000000 <lkmc_timer_callback>) at kernel/time/timer.c:1326
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[ 2.126472] Freeing unused kernel memory: 1264K │#2 0xffffffff810ab71f in expire_timers (head=<optimized out>,
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[ 2.126706] Write protecting the kernel read-only data: 16384k │ base=<optimized out>) at kernel/time/timer.c:1363
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[ 2.129388] Freeing unused kernel memory: 2024K │#3 __run_timers (base=<optimized out>) at kernel/time/timer.c:1666
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[ 2.139370] Freeing unused kernel memory: 1284K │#4 run_timer_softirq (h=<optimized out>) at kernel/time/timer.c:1692
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[ 2.246231] EXT4-fs (vda): warning: mounting unchecked fs, running e2fsck isd│#5 0xffffffff81a000cc in __do_softirq () at kernel/softirq.c:285
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[ 2.259574] EXT4-fs (vda): re-mounted. Opts: block_validity,barrier,user_xatr│#6 0xffffffff810577cc in invoke_softirq () at kernel/softirq.c:365
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hello S98 │#7 irq_exit () at kernel/softirq.c:405
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│#8 0xffffffff818021ba in exiting_irq () at ./arch/x86/include/asm/apic.h:541
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Apr 15 23:59:23 login[49]: root login on 'console' │#9 smp_apic_timer_interrupt (regs=<optimized out>)
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hello /root/.profile │ at arch/x86/kernel/apic/apic.c:1052
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# insmod /timer.ko │#10 0xffffffff8180190f in apic_timer_interrupt ()
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[ 6.791945] timer: loading out-of-tree module taints kernel. │ at arch/x86/entry/entry_64.S:857
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# [ 7.821621] 4294894248 │#11 0xffffffff82003df8 in init_thread_union ()
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[ 8.851385] 4294894504 │#12 0x0000000000000000 in ?? ()
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│(gdb)
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....
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All available modules can be found in the link:kernel_module/[`kernel_module` directory].
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@@ -673,14 +715,47 @@ And you now control the counting on the first shell from GDB!
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When you hit `Ctrl-C`, if we happen to be inside kernel code at that point, which is very likely if there are no heavy background tasks waiting, and we are just waiting on a `sleep` type system call of the command prompt, we can already see the source for the random place inside the kernel where we stopped.
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=== tmux multi terminal
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=== tmux
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tmux just makes things even more fun by allowing us to see both terminals at once without dragging windows around! https://unix.stackexchange.com/questions/152738/how-to-split-a-new-window-and-run-a-command-in-this-new-window-using-tmux/432111#432111
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https://unix.stackexchange.com/questions/152738/how-to-split-a-new-window-and-run-a-command-in-this-new-window-using-tmux/432111#432111
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tmux just makes things even more fun by allowing us to see both terminals at once without dragging windows around!
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....
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./tmu ./rungdb && ./run -d
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./run -du
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....
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Gives two panes:
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* left: usual QEMU
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* right: gdb
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and focuses on the GDB pane.
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To start again, switch back to the QEMU (`<prefix>-o`) pane, and re-run:
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....
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./run -du
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....
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This automatically kills the GDB pane.
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To quit for good, exit GDB, and quit the right shell with `Ctrl-D`.
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Pass extra GDB arguments with:
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....
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./run -du -U start_kernel
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....
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If you are using gem5 instead of QEMU, `-u` has a different effect: it opens the gem5 terminal instead of the debugger:
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....
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./run -gu
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....
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If you also want to use the debugger with gem5, you will need to create your own panes or windows.
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=== GDB step debug kernel module
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http://stackoverflow.com/questions/28607538/how-to-debug-linux-kernel-modules-with-qemu/44095831#44095831
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17
run
17
run
@@ -27,11 +27,13 @@ initramfs=false
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memory=256M
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nographic=true
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root=
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tmux=false
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tmux_args=
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# A dummy value that is already turned on by default and does not produce large output,
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# just to prevent QEMU from emitting a warning that '' is not valid.
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trace_enable=pr_manager_run
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vnc=
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while getopts a:c:DdE:e:f:G:ghIiKkm:T:Vx OPT; do
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while getopts a:c:DdE:e:f:G:ghIiKkm:T:U:uVx OPT; do
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case "$OPT" in
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a)
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arch="$OPTARG"
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@@ -91,6 +93,12 @@ while getopts a:c:DdE:e:f:G:ghIiKkm:T:Vx OPT; do
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T)
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trace_enable="$OPTARG"
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;;
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U)
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tmux_args="$OPTARG"
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;;
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u)
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tmux=true
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;;
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x)
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nographic=false
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;;
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@@ -281,5 +289,12 @@ ${extra_flags} \
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;;
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esac
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fi
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if "$tmux"; then
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if "$debug"; then
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eval "./tmu ./rungdb -a "${arch}" ${tmux_args}"
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elif "$gem5"; then
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eval "./tmu 'sleep 1;./gem5-shell'"
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fi
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fi
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echo "$cmd" | tee "${out_arch_dir}/run.sh"
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eval "$cmd"
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@@ -35,7 +35,7 @@
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|`-K` | |Use KVM. Only works if guest arch == host arch.
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|`-k` | |Enable KGDB.
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|`-m` | |Set the memory size of the guest. E.g.: `-m 512M`. Default: `256M`.
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The default is the minimum ammount that boots all archs without extra
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The default is the minimum amount that boots all archs without extra
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options added. Anything lower will lead some arch to fail to boot.
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Any
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|`-T` | |Enable extra QEMU trace events.
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@@ -43,6 +43,13 @@
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some by default, e.g. `pr_manager_run`, and I don't know how to
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get rid of them. But those events are rare and should not impact
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performance, so we just ignore them for now.
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|`-U` | |Pass extra parameters to the program running on the `-u` tmux split.
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|`-u` | |Create a tmUx split the window.
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You must already be inside of a `tmux` session to use this option.
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* on the main window, run the emulator as usual
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* on the split:
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** if on QEMU and `-d` is given, GDB
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** if on gem5, the gem5 terminal
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|`-V` | |Run QEMU with VNC instead of the default SDL.
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Connect to it with: `vinagre localhost:5900`.
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|`-x` | |Run in graphic mode. Mnemonic: X11.
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BIN
screenshot.png
BIN
screenshot.png
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