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console: make awesome
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Ciro Santilli 六四事件 法轮功
64
README.adoc
64
README.adoc
@@ -1832,34 +1832,68 @@ It is useless with QEMU since we already have full system visibility with `-gdb`
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Cheaper than JTAG (free) and easier to setup (all you need is serial), but with less visibility as it depends on the kernel working, so e.g.: dies on panic, does not see boot sequence.
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Usage:
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First run the kernel with:
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....
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./run --kgdb
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./run-gdb --kgdb
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....
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In GDB:
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this passes the following options on the kernel CLI:
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....
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c
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kgdbwait kgdboc=ttyS1,115200
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....
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In QEMU:
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`kgdbwait` tells the kernel to wait for KGDB to connect.
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So the kernel sets things up enough for KGDB to start working, and then boot pauses waiting for connection:
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....
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<6>[ 4.866050] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
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<6>[ 4.893205] 00:05: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
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<6>[ 4.916271] 00:06: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A
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<6>[ 4.987771] KGDB: Registered I/O driver kgdboc
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<2>[ 4.996053] KGDB: Waiting for connection from remote gdb...
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Entering kdb (current=0x(____ptrval____), pid 1) on processor 0 due to Keyboard Entry
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[0]kdb>
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....
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KGDB expects the connection at `ttyS1`, our second serial port after `ttyS0` which contains the terminal.
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So now we can connect to the serial port with GDB:
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....
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./run-gdb --kgdb --no-continue
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....
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Once GDB connects, it is left inside the function `kgdb_breakpoint`.
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So now we can set breakpoints and continue as usual.
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For example, in GDB:
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....
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continue
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....
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Then in QEMU:
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....
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/count.sh &
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/kgdb.sh
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....
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In GDB:
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link:rootfs_overlay:kgdb.sh[] pauses the kernel for KGDB, and gives control back to GDB.
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And now in GDB we do the usual:
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....
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b __x64_sys_write
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c
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c
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c
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c
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break __x64_sys_write
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continue
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continue
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continue
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continue
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....
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And now you can count from GDB!
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@@ -1873,9 +1907,11 @@ See also:
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=== KGDB ARM
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GDB not connecting to KGDB in ARM. Possibly linked to `-serial stdio`. See also: https://stackoverflow.com/questions/14155577/how-to-use-kgdb-on-arm
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GDB not connecting to KGDB in `arm` and `aarch64`.
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Main shell just falls on:
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Main question: https://stackoverflow.com/questions/14155577/how-to-use-kgdb-on-arm
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The main console just hangs on:
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....
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Entering kdb (current=0xf8ce07d3, pid 1) due to Keyboard Entry
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@@ -1893,6 +1929,8 @@ Ignoring packet error, continuing...
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Remote replied unexpectedly to 'vMustReplyEmpty': timeout
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....
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I wanted to try to and run run KGDB on a second serial to see if it makes a difference, but QEMU `-M virt` does not seem to support it: https://stackoverflow.com/questions/53080745/can-qemu-m-virt-on-arm-aarch64-have-multiple-serial-ttys-like-such-as-pl011-t
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=== KGDB kernel modules
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In QEMU:
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@@ -670,6 +670,7 @@ def setup(parser):
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args.gem5_build_id = args.gem5_worktree
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this_module.machine = args.machine
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this_module.setup_dry_run_arguments(args)
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this_module.is_arm = False
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if args.arch == 'arm':
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this_module.armv = 7
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this_module.gem5_arch = 'ARM'
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@@ -683,6 +684,7 @@ def setup(parser):
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else:
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if this_module.machine is None:
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this_module.machine = 'virt'
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this_module.is_arm = True
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elif args.arch == 'aarch64':
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this_module.armv = 8
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this_module.gem5_arch = 'ARM'
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@@ -696,6 +698,7 @@ def setup(parser):
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else:
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if this_module.machine is None:
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this_module.machine = 'virt'
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this_module.is_arm = True
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elif args.arch == 'x86_64':
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this_module.crosstool_ng_toolchain_prefix = 'x86_64-unknown-elf'
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this_module.gem5_arch = 'X86'
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@@ -117,6 +117,7 @@ scons \
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if "$baremetal"; then
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pkgs="${pkgs} \
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docbook2x \
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libtool-bin \
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"
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fi
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command -v apt-get >/dev/null 2>&1 || {
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31
run
31
run
@@ -81,11 +81,22 @@ def main(args, extra_args=None):
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kernel_cli += ' {}=/eval_base64.sh'.format(initarg)
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kernel_cli_after_dash += ' lkmc_eval="{}"'.format(common.base64_encode(args.eval))
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if not args.graphic:
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if args.arch == 'x86_64':
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kernel_cli += ' console=ttyS0'
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else:
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kernel_cli += ' console=ttyAMA0'
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extra_qemu_args.append('-nographic')
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console = None
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console_type = None
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console_count = 0
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if args.arch == 'x86_64':
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console_type = 'ttyS'
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elif common.is_arm:
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console_type = 'ttyAMA'
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console = '{}{}'.format(console_type, console_count)
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if not (args.arch == 'x86_64' and args.graphic):
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console_count += 1
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kernel_cli += ' console={}'.format(console)
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extra_console = '{}{}'.format(console_type, console_count)
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console_count += 1
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if args.kgdb:
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kernel_cli += ' kgdboc={},115200'.format(console)
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if kernel_cli_after_dash:
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kernel_cli += " -{}".format(kernel_cli_after_dash)
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extra_env = {}
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@@ -161,12 +172,12 @@ def main(args, extra_args=None):
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if args.arch == 'x86_64':
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if args.kvm:
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cmd.extend(['--cpu-type', 'X86KvmCPU'])
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cmd.extend(['--command-line', 'earlyprintk=ttyS0 lpj=7999923 root=/dev/sda {}'.format(kernel_cli)])
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elif args.arch == 'arm' or args.arch == 'aarch64':
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cmd.extend(['--command-line', 'earlyprintk={} lpj=7999923 root=/dev/sda {}'.format(console, kernel_cli)])
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elif common.is_arm:
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# TODO why is it mandatory to pass mem= here? Not true for QEMU.
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# Anything smaller than physical blows up as expected, but why can't it auto-detect the right value?
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cmd.extend([
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'--command-line', 'earlyprintk=pl011,0x1c090000 console=ttyAMA0 lpj=19988480 rw loglevel=8 mem={} root=/dev/sda {}'.format(memory, kernel_cli),
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'--command-line', 'earlyprintk=pl011,0x1c090000 lpj=19988480 rw loglevel=8 mem={} root=/dev/sda {}'.format(memory, kernel_cli),
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'--dtb-filename', os.path.join(common.gem5_system_dir, 'arm', 'dt', 'armv{}_gem5_v1_{}cpu.dtb'.format(common.armv, args.cpus)),
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'--machine-type', common.machine,
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'--param', 'system.panic_on_panic = True',
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@@ -295,17 +306,13 @@ def main(args, extra_args=None):
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else:
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virtio_gpu_pci = ['-device', 'virtio-gpu-pci']
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if args.arch == 'x86_64':
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if args.kgdb:
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kernel_cli += ' kgdboc=ttyS1,115200'
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append = ['-append', '{} nopat {}'.format(root, kernel_cli)]
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cmd.extend([
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'-M', common.machine,
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'-device', 'edu',
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])
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elif args.arch == 'arm' or args.arch == 'aarch64':
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elif common.is_arm:
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extra_emulator_args.append('-semihosting')
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if args.kgdb:
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kernel_cli += ' kgdboc=ttyAMA0,115200'
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if args.arch == 'arm':
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cpu = 'cortex-a15'
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else:
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