Ping^2 ?
/mjt
27.10.2012 12:31, Michael Tokarev wrote:
> Ping?
>
> On 19.09.2012 12:08, Michael Tokarev wrote:
>> This reverts commit 67c5322d7000fd105a926eec44bc1765b7d70bdd:
>>
>> I'm not sure if the retry logic has ever worked when not using FIFO
>> mode. I
>> found this while writing a test case although code inspection confirms
>> it is
>> definitely broken.
>>
>> The TSR retry logic will never actually happen because it is guarded by
>> an
>> 'if (s->tsr_rety > 0)' but this is the only place that can ever make the
>> variable greater than zero. That effectively makes the retry logic an
>> 'if (0)
>>
>> I believe this is a typo and the intention was >= 0. Once this is fixed
>> thoug
>> I see double transmits with my test case. This is because in the non
>> FIFO
>> case, serial_xmit may get invoked while LSR.THRE is still high because
>> the
>> character was processed but the retransmit timer was still active.
>>
>> We can handle this by simply checking for LSR.THRE and returning early.
>> It's
>> possible that the FIFO paths also need some attention.
>>
>> Cc: Stefano Stabellini <stefano.stabell...@eu.citrix.com>
>> Signed-off-by: Anthony Liguori <aligu...@us.ibm.com>
>>
>> Even if the previous logic was never worked, new logic breaks stuff -
>> namely,
>>
>> qemu -enable-kvm -nographic -kernel /boot/vmlinuz-$(uname -r) -append
>> console=ttyS0 -serial pty
>>
>> the above command will cause the virtual machine to stuck at startup
>> using 100% CPU till one connects to the pty and sends any char to it.
>>
>> Note this is rather typical invocation for various headless virtual
>> machines by libvirt.
>>
>> So revert this change for now, till a better solution will be found.
>>
>> Signed-off-by: Michael Tokarev <m...@tls.msk.ru>
>> ---
>> hw/serial.c | 4 +---
>> 1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/hw/serial.c b/hw/serial.c
>> index a421d1e..df54de2 100644
>> --- a/hw/serial.c
>> +++ b/hw/serial.c
>> @@ -327,8 +327,6 @@ static void serial_xmit(void *opaque)
>> s->tsr = fifo_get(s,XMIT_FIFO);
>> if (!s->xmit_fifo.count)
>> s->lsr |= UART_LSR_THRE;
>> - } else if ((s->lsr & UART_LSR_THRE)) {
>> - return;
>> } else {
>> s->tsr = s->thr;
>> s->lsr |= UART_LSR_THRE;
>> @@ -340,7 +338,7 @@ static void serial_xmit(void *opaque)
>> /* in loopback mode, say that we just received a char */
>> serial_receive1(s, &s->tsr, 1);
>> } else if (qemu_chr_fe_write(s->chr, &s->tsr, 1) != 1) {
>> - if ((s->tsr_retry >= 0) && (s->tsr_retry <= MAX_XMIT_RETRY)) {
>> + if ((s->tsr_retry > 0) && (s->tsr_retry <= MAX_XMIT_RETRY)) {
>> s->tsr_retry++;
>> qemu_mod_timer(s->transmit_timer, new_xmit_ts +
>> s->char_transmit_time);
>> return;
>
>
