From: Alexander Mikhalitsyn <[email protected]> Currently, when Incus issues "chardev-change" QMP command to change chardev backend from ringbuf to socket it receives an error (with aarch64 VM): "Chardev user does not support chardev hotswap" [1], [2]
Let's fix this by properly implementing BackendChangeHandler for pl011. Please, note that we have to "replay" CHR_IOCTL_SERIAL_SET_BREAK, because if BRK bit was set before backend change (i.e. (s->lcr & LCR_BRK) is true), then after change we need to send break to a new backend too. Link: https://discuss.linuxcontainers.org/t/unable-to-connect-to-vm-console-on-arm-architecture/23096/3 [1] Link: https://github.com/lxc/distrobuilder/issues/892 [2] Reported-by: Stéphane Graber <[email protected]> Reviewed-by: Alex Bennée <[email protected]> Signed-off-by: Alexander Mikhalitsyn <[email protected]> --- v4: - changed pl011_set_break() signature [ as suggested by Peter Maydell ] v3: - introduced pl011_set_handlers() [ as suggested by Alex Bennée ] - introduced pl011_set_break() [ as suggested by Philippe Mathieu-Daudé ] v2: - fixed a typo in commit author name [ I did `git format-patch` and copied this patch from my Raspberry PI dev/test machine and it turns out that I have a stupid typo in my `git config get user.name` on that machine. ] - added RWB tag from Alex Bennée - adjusted a commit message --- hw/char/pl011.c | 31 ++++++++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-) diff --git a/hw/char/pl011.c b/hw/char/pl011.c index cb12c3e224f..5ad9e7358d5 100644 --- a/hw/char/pl011.c +++ b/hw/char/pl011.c @@ -425,6 +425,11 @@ static void pl011_loopback_break(PL011State *s, int brk_enable) } } +static inline void pl011_set_break(PL011State *s, int brk_enable) +{ + qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_BREAK, &brk_enable); +} + static void pl011_write(void *opaque, hwaddr offset, uint64_t value, unsigned size) { @@ -462,9 +467,8 @@ static void pl011_write(void *opaque, hwaddr offset, pl011_reset_tx_fifo(s); } if ((s->lcr ^ value) & LCR_BRK) { - int break_enable = value & LCR_BRK; - qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_BREAK, - &break_enable); + bool break_enable = value & LCR_BRK; + pl011_set_break(s, break_enable); pl011_loopback_break(s, break_enable); } s->lcr = value; @@ -660,12 +664,29 @@ static void pl011_init(Object *obj) s->id = pl011_id_arm; } +static int pl011_be_change(void *opaque); + +static inline void pl011_set_handlers(PL011State *s) +{ + qemu_chr_fe_set_handlers(&s->chr, pl011_can_receive, pl011_receive, + pl011_event, pl011_be_change, s, NULL, true); +} + +static int pl011_be_change(void *opaque) +{ + PL011State *s = opaque; + + pl011_set_handlers(s); + pl011_set_break(s, s->lcr & LCR_BRK); + + return 0; +} + static void pl011_realize(DeviceState *dev, Error **errp) { PL011State *s = PL011(dev); - qemu_chr_fe_set_handlers(&s->chr, pl011_can_receive, pl011_receive, - pl011_event, NULL, s, NULL, true); + pl011_set_handlers(s); } static void pl011_reset(DeviceState *dev) -- 2.47.3
