vt
看看
https://unix.stackexchange.com/questions/32884/which-virtual-terminal-is-a-given-x-process-running-on https://stackoverflow.com/questions/3034567/how-do-i-find-the-current-virtual-terminal https://askubuntu.com/questions/33078/what-is-a-virtual-terminal-for
vt
没有图形界面，默认进入的就是 vt
bmc 的时候也是如此的
static void sysrq_handle_showregs(u8 key)
{
struct pt_regs *regs = NULL;
if (in_hardirq())
regs = get_irq_regs();
if (regs)
show_regs(regs);
perf_event_print_debug();
}
[ 248.671749] sysrq: HELP : loglevel(0-9) reboot(b) crash(c) terminate-all-tasks(e) memory-full-oom-kill(f) kill-all
-tasks(i) thaw-filesystems(j) sak(k) show-backtrace-all-active-cpus(l) show-memory-usage(m) nice-all-RT-tasks(n) powe
roff(o) show-registers(p) show-all-timers(q) unraw(r) sync(s) show-task-states(t) unmount(u) force-fb(V) show-blocked
-tasks(w) dump-ftrace-buffer(z)
[ 252.998756] sysrq: Show Regs
[ 253.002434] CPU: 10 PID: 0 Comm: swapper/10 Kdump: loaded Tainted: G OE martins3-4.19.x86
_64 #1
[ 253.014003] Hardware name: Suma R6240H0/62DB32, BIOS CXYH051029 09/06/2023
[ 253.021573] RIP: 0010:native_safe_halt+0xe/0x10
[ 253.026796] Code: eb bd 90 90 90 90 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d f6 0c 53 00 f4 c3 66 90 e9 07 00 00
00 0f 00 2d e6 0c 53 00 fb f4 <c3> 90 0f 1f 44 00 00 41 55 41 54 55 53 e8 b0 6f 85 ff 65 8b 2d c9
[ 253.046926] RSP: 0018:ffffb2dd0025fea8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffde
[ 253.055184] RAX: ffffffffa90d7160 RBX: 000000000000000a RCX: 7fffffc5f636d1aa
[ 253.063021] RDX: 7fffffffffffffff RSI: 000000000000000a RDI: ffff956cff8a3d40
[ 253.070862] RBP: 000000000000000a R08: ffff956cff89dc80 R09: 0000000000000000
[ 253.078705] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
[ 253.086549] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[ 253.094393] FS: 00007f6d9fb79740(0000) GS:ffff956cff880000(0000) knlGS:0000000000000000
[ 253.103199] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 253.109672] CR2: 00007f6d92e31020 CR3: 0000007830c0a000 CR4: 00000000003406e0
[ 253.117542] Call Trace:
[ 253.120735] default_idle+0x1c/0x140
[ 253.125063] do_idle+0x1aa/0x250
[ 253.129020] cpu_startup_entry+0x6f/0x80
[ 253.133667] start_secondary+0x18d/0x1e0
[ 253.138310] secondary_startup_64+0xb6/0xc0
[ 253.143207] CPU#10: active: 0000000000000001
[ 253.148535] CPU#10: gen-PMC0 ctrl: 0000000000530076
[ 253.154384] CPU#10: gen-PMC0 count: 0000fffb7a1b6a0d
[ 253.160215] CPU#10: gen-PMC0 left: 000000051f5c2910
[ 253.166032] CPU#10: gen-PMC1 ctrl: 0000000000000000
[ 253.171839] CPU#10: gen-PMC1 count: 0000000000000000
[ 253.177627] CPU#10: gen-PMC1 left: 0000000000000000
[ 253.183399] CPU#10: gen-PMC2 ctrl: 0000000000000000
[ 253.189154] CPU#10: gen-PMC2 count: 0000000000000000
[ 253.194899] CPU#10: gen-PMC2 left: 0000000000000000
[ 253.200638] CPU#10: gen-PMC3 ctrl: 0000000000000000
[ 253.206366] CPU#10: gen-PMC3 count: 0000000000000000
[ 253.212076] CPU#10: gen-PMC3 left: 0000000000000000
[ 253.217782] CPU#10: gen-PMC4 ctrl: 0000000000000000
[ 253.223474] CPU#10: gen-PMC4 count: 0000000000000000
[ 253.229152] CPU#10: gen-PMC4 left: 0000000000000000
[ 253.234811] CPU#10: gen-PMC5 ctrl: 0000000000000000
[ 253.240451] CPU#10: gen-PMC5 count: 0000000000000000
[ 253.246077] CPU#10: gen-PMC5 left: 0000000000000000
drivers/tty/vt/keyboard.c 中
这里也会调用 show_state ，和 sysrq 一样的
如果使用 fn_show_ptregs 需要判断 in_hardirq() 吗?
sysrq_handle_showallcpus 中判断过，但是这里是没有的，而且奇怪的是，这样的话，岂不是 sysrq 和 vt 的功能是重叠的
static void fn_show_ptregs(struct vc_data *vc)
{
struct pt_regs *regs = get_irq_regs();
if (regs)
show_regs(regs);
}
测试下，n100 中不要包含 drm 驱动，会有什么影响?
我猜测 vt console 直接无法显示吧
原来 drivers/tty/vt/keyboard.c 中的代码一直都是可以调用的
@[
fn_enter+5
kbd_event+959
input_handle_events_default+66
input_pass_values+289
input_event_dispose+322
input_event+83
hidinput_report_event+55
hid_report_raw_event+320
hid_input_report+251
hid_irq_in+464
__usb_hcd_giveback_urb+145
usb_giveback_urb_bh+169
process_one_work+325
bh_worker+555
tasklet_hi_action+19
handle_softirqs+220
irq_exit_rcu+161
common_interrupt+133
asm_common_interrupt+38
cpuidle_enter_state+198
cpuidle_enter+45
do_idle+412
cpu_startup_entry+41
start_secondary+247
common_startup_64+300
]: 6
似乎 Ctrl + Alt + F2 和 Ctrl + Alt + F1 都不是一个东西
功能定位有不同的
有趣的 manual
https://manpages.ubuntu.com/manpages/plucky/man4/vt.4freebsd.html
想不到 windows 也是考虑这个的
https://learn.microsoft.com/en-us/windows/console/console-virtual-terminal-sequences
理解这个
https://wiki.archlinux.org/title/Linux_console
这个 freebsd 也是有的
https://docs-archive.freebsd.org/doc/11.4-RELEASE/usr/local/share/doc/freebsd/handbook/consoles.html
看看，写的相当好，可以看看 vt 去掉之后的效果
https://www.reddit.com/r/linux/comments/10eccv9/config_vtn_in_2023/
依赖 VT 的一些 config
CONFIG_VT=y
CONFIG_CONSOLE_TRANSLATIONS=y
CONFIG_VT_CONSOLE=y
CONFIG_VT_CONSOLE_SLEEP=y
# CONFIG_VT_HW_CONSOLE_BINDING is not set
CONFIG_VGA_CONSOLE=y
CONFIG_DUMMY_CONSOLE=y
CONFIG_DUMMY_CONSOLE_COLUMNS=80
CONFIG_DUMMY_CONSOLE_ROWS=25
注意， 把 VT 去掉之后，console=ttyS0 不受影响
只有 vnc 功能收到影响
忽然意识到，vt 是非常复杂的，他是需要键盘鼠标的
在 vnc 中 enter 的效果
@[
fn_enter+5
kbd_event+959
input_handle_events_default+66
input_pass_values+289
input_event_dispose+322
input_event+83
atkbd_receive_byte+1689
ps2_interrupt+158
serio_interrupt+71
i8042_handle_data+240
i8042_interrupt+17
__handle_irq_event_percpu+71
handle_irq_event+56
handle_edge_irq+139
__common_interrupt+59
common_interrupt+128
asm_common_interrupt+38
default_idle+15
default_idle_call+48
do_idle+437
cpu_startup_entry+41
start_secondary+247
common_startup_64+300
]: 5
原来如此:
@[
fbcon_putcs+0
con_write+32
n_tty_write+380
file_tty_write.isra.0+300
redirected_tty_write+268
vfs_write+544
ksys_write+120
__arm64_sys_write+36
invoke_syscall.constprop.0+88
do_el0_svc+72
el0_svc+64
el0t_64_sync_handler+268
el0t_64_sync+408
]: 1
🧀 cat /sys/class/vtconsole/vtcon*/name
(S) dummy device
(M) frame buffer device
🧀 ls /sys/class/graphics/fb*
/sys/class/graphics/fb0:
bits_per_pixel console dev mode name power state subsystem virtual_size
blank cursor device modes pan rotate stride uevent
/sys/class/graphics/fbcon:
cursor_blink power rotate rotate_all subsystem uevent
cat /sys/class/graphics/fb*/name hibmcdrmfb
i915drmfb : intel 机器
🧀 ls -la /sys/class/drm/
lrwxrwxrwx - root 6 Apr 14:46 card0 -> ../../devices/pci0000:00/0000:00:11.0/0000:03:00.0/drm/card0
lrwxrwxrwx - root 6 Apr 14:46 card0-VGA-1 -> ../../devices/pci0000:00/0000:00:11.0/0000:03:00.0/drm/card0/card0-VGA-1
.r--r--r-- 4.1k root 6 Apr 14:46 version
大致的关联关系是这个样子的: /dev/tty0 -> /sys/devices/virtual/tty/tty0 -> vtcon1 -> /sys/class/graphics/fb0 -> /sys/class/drm/card0
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