Re: [Qemu-devel] [PATCH v2] Remove unwanted crlf conversion in serial

[Paolo Bonzini]

On 24/05/2018 07:36, Thomas Huth wrote:
> On 23.05.2018 21:50, Patryk Olszewski wrote:
>> This patch fixes bug in serial that made it almost impossible for guest
>> to communicate with devices through host's serial.
>>
>> OPOST flag in c_oflag enables output processing letting other flags in
>> c_oflag take effect. Usually in c_oflag ONLCR flag is also set, which
>> causes crlf to be sent in place of lf. This breaks binary transmissions.
>> Unsetting OPOST flag turns off any output processing which fixes the bug.
>>
>> Bug reports related:
>> https://bugs.launchpad.net/qemu/+bug/1772086
>> https://bugs.launchpad.net/qemu/+bug/1407813
>> https://bugs.launchpad.net/qemu/+bug/1715296
>> also
>> https://lists.nongnu.org/archive/html/qemu-devel/2006-06/msg00196.html
>>
>> Signed-off-by: Patryk Olszewski <address@hidden>
>> ---
>>  chardev/char-serial.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/chardev/char-serial.c b/chardev/char-serial.c
>> index feb52e5..ae548d2 100644
>> --- a/chardev/char-serial.c
>> +++ b/chardev/char-serial.c
>> @@ -139,7 +139,7 @@ static void tty_serial_init(int fd, int speed,
>>  
>>      tty.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
>>                       | INLCR | IGNCR | ICRNL | IXON);
>> -    tty.c_oflag |= OPOST;
>> +    tty.c_oflag &= ~OPOST;
>>      tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);
>>      tty.c_cflag &= ~(CSIZE | PARENB | PARODD | CRTSCTS | CSTOPB);
>>      switch (data_bits) {
>>
> 
> I think this bug has good chances to win the price "Oldest bug of the
> year". If we'd wait one more months, it has its 15th anniversary: The
> code has originally been added in 2003, see commit 0824d6fc674084519c85,
> it has just been moved around to other files afterwards. Thus this is
> almost as old as QEMU itself!

It was also already fixed once in

commit 64b7b7334b92c1fdc1bb7d3d1afc342656c59539
Author: aurel32 <address@hidden>
Date:   Mon May 5 10:05:31 2008 +0000

    Put Pseudo-TTY in rawmode for char devices

    (Daniel P. Berrange)

Queued, thanks.

Paolo