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[Qemu-devel] Bug report: Windows and serial port lager than COM9
From: |
Dietrich Lauter |
Subject: |
[Qemu-devel] Bug report: Windows and serial port lager than COM9 |
Date: |
Mon, 30 Mar 2009 01:23:58 -0800 |
Hi,
I run into a smaller bug using QEMU (0.10.1) on Windows. I was able to track
down the issue and also found a solution. I want to share with you this fix. I
hope I did it in the proper way, so you might integrate it.
Solution:
I made a change in the function "win_chr_init(...)" of the source file
"qemu-char.c" . I took parts from the function "win_chr_pipe_init(...)" to
implement the fix, as a pipe needs to be open using a similar name format than
for serial ports larger than COM9.
The output of the a diff looks like the following:
$ diff qemu-char.c.ORG qemu-char.c
1389a1390
> char openname[256];
1402c1403,1404
< s->hcom = CreateFile(filename, GENERIC_READ|GENERIC_WRITE, 0, NULL,
---
> snprintf(openname, sizeof(openname), "\\\\.\\%s", filename);
> s->hcom = CreateFile(openname, GENERIC_READ|GENERIC_WRITE, 0, NULL,
Background:
I had tested the ARM-Emulator from QEMU using the parameter "-serial" to
connect to one of my virutal serial ports (com0com). The port, I wanted to use,
has the name "COM50:". When I started the emulator using command
"qemu-system-arm ... -serial COM50" I got the following error message:
Failed CreateFile (2)
qemu: could not open serial device 'COM50'
Reading the definition for the CreateFile function, I saw that for serial ports
lager than COM9 the format of FileName should be in a specific format e.g.
"\\.\COM10". This specific handling is also described in the following article:
HOWTO: Specify Serial Ports Larger than COM9
(http://support.microsoft.com/kb/115831)
Kind regards,
Dietrich
PS: That's my first posting ... so please let me known if I was doing something
wrong.
=== (new) qemu-char.c ===
...
static int win_chr_init(CharDriverState *chr, const char *filename)
{
WinCharState *s = chr->opaque;
COMMCONFIG comcfg;
COMMTIMEOUTS cto = { 0, 0, 0, 0, 0};
COMSTAT comstat;
DWORD size;
DWORD err;
char openname[256];
s->hsend = CreateEvent(NULL, TRUE, FALSE, NULL);
if (!s->hsend) {
fprintf(stderr, "Failed CreateEvent\n");
goto fail;
}
s->hrecv = CreateEvent(NULL, TRUE, FALSE, NULL);
if (!s->hrecv) {
fprintf(stderr, "Failed CreateEvent\n");
goto fail;
}
snprintf(openname, sizeof(openname), "\\\\.\\%s", filename);
s->hcom = CreateFile(openname, GENERIC_READ|GENERIC_WRITE, 0, NULL,
OPEN_EXISTING, FILE_FLAG_OVERLAPPED, 0);
...
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