On Wed, 12 Mar 2025 at 13:36, Peter Maydell <[email protected]> wrote: > > On Tue, 11 Mar 2025 at 15:37, Paolo Bonzini <[email protected]> wrote: > > > > The guest does not control whether characters are sent on the UART. > > Sending them before the guest happens to boot will now result in a > > "guest error" log entry that is only because of timing, even if the > > guest _would_ later setup the receiver correctly. > > > > This reverts commit abf2b6a028670bd2890bb3aee7e103fe53e4b0df, apart > > from adding the comment. > > > > Cc: Philippe Mathieu-Daudé <[email protected]> > > Cc: Peter Maydell <[email protected]> > > Signed-off-by: Paolo Bonzini <[email protected]> > > --- > > hw/char/pl011.c | 12 ++---------- > > 1 file changed, 2 insertions(+), 10 deletions(-) > > > > diff --git a/hw/char/pl011.c b/hw/char/pl011.c > > index 23a9db8c57c..efca8baecd7 100644 > > --- a/hw/char/pl011.c > > +++ b/hw/char/pl011.c > > @@ -85,7 +85,6 @@ DeviceState *pl011_create(hwaddr addr, qemu_irq irq, > > Chardev *chr) > > #define CR_OUT1 (1 << 12) > > #define CR_RTS (1 << 11) > > #define CR_DTR (1 << 10) > > -#define CR_RXE (1 << 9) > > #define CR_TXE (1 << 8) > > #define CR_LBE (1 << 7) > > #define CR_UARTEN (1 << 0) > > @@ -490,16 +489,9 @@ static int pl011_can_receive(void *opaque) > > unsigned fifo_depth = pl011_get_fifo_depth(s); > > unsigned fifo_available = fifo_depth - s->read_count; > > > > - if (!(s->cr & CR_UARTEN)) { > > - qemu_log_mask(LOG_GUEST_ERROR, > > - "PL011 receiving data on disabled UART\n"); > > - } > > - if (!(s->cr & CR_RXE)) { > > - qemu_log_mask(LOG_GUEST_ERROR, > > - "PL011 receiving data on disabled RX UART\n"); > > - } > > + /* Should check enable and return 0? */ > > We decided deliberately not to check the enable and return 0 > here, as described in the commit message of abf2b6a028670bd: > we think there's too likely to be existing works-on-QEMU code > out there that doesn't ever set the enable bits. > > Otherwise, yes, agreed with the revert.
Oh, and I just realized that the right place to diagnose "guest didn't enable the UART" would be when it reads/writes the data register while the enable bits are clear. -- PMM
