On 06.06.2025 09:06, dm...@proton.me wrote: > On Thu, Jun 05, 2025 at 08:18:34AM +0200, Jan Beulich wrote: >> On 05.06.2025 02:46, dm...@proton.me wrote: >>> From: Denis Mukhin <dmuk...@ford.com> >>> >>> If virtual UART from domain X prints on the physical console, the behavior >>> is >>> updated to (see [1]): >>> - console focus in domain X: do not prefix messages; >>> - no console focus in domain X: prefix all messages with "(dX)". >>> >>> Use guest_printk() without rate-limiting in all current in-hypervisor UART >>> emulators. That aligns the behavior with debug I/O port 0xe9 handler on x86 >>> and >>> slightly improves the logging since guest_printk() already prints the domain >>> ID. guest_printk() was modified to account for console focus ownership. >>> >>> Modify guest_console_write() for hardware domain case by adding domain ID to >>> the message when hwdom does not have console focus. >>> >>> [1] >>> https://lore.kernel.org/xen-devel/alpine.DEB.2.22.394.2412121655360.463523@ubuntu-linux-20-04-desktop/ >>> Signed-off-by: Denis Mukhin <dmuk...@ford.com> >>> --- >>> Changes since v1: >>> - dropped change for debug port and for HYPERVISOR_console_io hypercall >> >> Yet then what about ... >> >>> --- a/xen/arch/arm/vuart.c >>> +++ b/xen/arch/arm/vuart.c >>> @@ -89,7 +89,7 @@ static void vuart_print_char(struct vcpu *v, char c) >>> if ( c != '\n' ) >>> uart->buf[uart->idx++] = '\n'; >>> uart->buf[uart->idx] = '\0'; >>> - printk(XENLOG_G_DEBUG "DOM%u: %s", d->domain_id, uart->buf); >>> + guest_printk(d, "%s", uart->buf); >>> uart->idx = 0; >>> } >>> spin_unlock(&uart->lock); >> >> ... this dropping of XENLOG_G_DEBUG? In fact I'd have expected such to >> be _added_ where presently missing. > > vUART is a debugging facility. This flavor of UART is specifically for guest > OS > early boot debugging. > I think it is not desirable to potentially lose guest messages while doing > such > early guest OS boot debugging.
That is the host admin's decision, not a policy we should enforce. Jan
