[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v2 2/2] xen/console: unify printout behavior for UART emulators
On Thu, Jun 05, 2025 at 08:18:34AM +0200, Jan Beulich wrote: > On 05.06.2025 02:46, dmkhn@xxxxxxxxx wrote: > > From: Denis Mukhin <dmukhin@xxxxxxxx> > > > > 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 <dmukhin@xxxxxxxx> > > --- > > 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. > > Jan
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