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[Qemu-devel] [PATCH 04/15] serial: fix lost character after sysrq
From: |
Glauber Costa |
Subject: |
[Qemu-devel] [PATCH 04/15] serial: fix lost character after sysrq |
Date: |
Wed, 17 Jun 2009 13:09:53 -0400 |
From: Jason Wessel <address@hidden>
After creating an automated regression test to test the sysrq
responses while running a linux image in qemu, I found that the
simulated uart was eating the character right after the sysrq about
75% of the time.
The problem is that the qemu sets the LSR_DR (data ready) bit on a
serial break. The automated tests can send a break and the sysrq
character quickly enough that the qemu serial fifo has a real
character available. When there is valid character in the fifo, it
gets consumed by the serial driver in the guest OS.
The real hardware also appears to set the LSR_DR but always appears to
have a null byte in this condition. This patch changes the qemu
behavior to match the tested characteristics of a real 16550 chip.
Signed-off-by: Jason Wessel <address@hidden>
Signed-off-by: Glauber Costa <address@hidden>
---
hw/serial.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/hw/serial.c b/hw/serial.c
index ac089fc..113829c 100644
--- a/hw/serial.c
+++ b/hw/serial.c
@@ -586,6 +586,8 @@ static int serial_can_receive(SerialState *s)
static void serial_receive_break(SerialState *s)
{
s->rbr = 0;
+ /* When the LSR_DR is set a null byte is pushed into the fifo */
+ fifo_put(s, RECV_FIFO, '\0');
s->lsr |= UART_LSR_BI | UART_LSR_DR;
serial_update_irq(s);
}
--
1.6.2.2
- [Qemu-devel] [GIT PULL 00/15] Stable branch update 2009-06-17, Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 01/15] net: Fix -net socket, listen (Jan Kiszka), Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 02/15] Minimal ethernet frame length is 64 bytes., Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 03/15] Don't send all gratuitous packets at once., Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 04/15] serial: fix lost character after sysrq,
Glauber Costa <=
- [Qemu-devel] [PATCH 05/15] e1000: Ignore reset command, Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 06/15] VNC: Fix memory allocation (wrong structure size)., Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 07/15] fix raw_pread_aligned return value, Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 08/15] BACKPORT: Register reset functions for e1000 and rtl8139, Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 09/15] BACKPORT: Update irqs on reset and device load, Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 10/15] BACKPORT: Add rtc reset function., Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 11/15] fix qemu_aio_flush, Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 12/15] QEMU KVM: i386: Fix the cpu reset state, Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 13/15] kvm: Fix IRQ injection into full queue, Glauber Costa, 2009/06/17
- [Qemu-devel] [PATCH 14/15] Prevent CD-ROM media eject while device is locked, Glauber Costa, 2009/06/17