qemu-log: default to stderr for logging output

Switch the default for qemu_log logging output from "/tmp/qemu.log"
to stderr. This is an incompatible change in some sense, but logging
is mostly used for debugging purposes so it shouldn't affect production
use. The previous behaviour can be obtained by adding "-D /tmp/qemu.log"
to the command line.

This change requires us to:
 * update all the documentation/help text (we take the opportunity
   to smooth out minor inconsistencies between the phrasing in
   linux-user/bsd-user/system help messages)
 * make linux-user and bsd-user defer to qemu-log for the default
   logging destination rather than overriding it themselves
 * ensure that all logfile closing is done via qemu_log_close()
   and that that function doesn't close stderr
as well as the obvious change to the behaviour of do_qemu_set_log()
when no logfile name has been specified.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-id: 1361901160-28729-1-git-send-email-peter.maydell@linaro.org
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 8 insertions, 10 deletions

diff --git a/bsd-user/main.c b/bsd-user/main.c
index 097fbfe432..cc8498187a 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -34,8 +34,6 @@
 #include "qemu/timer.h"
 #include "qemu/envlist.h"
 
-#define DEBUG_LOGFILE "/tmp/qemu.log"
-
 int singlestep;
 #if defined(CONFIG_USE_GUEST_BASE)
 unsigned long mmap_min_addr;
@@ -691,11 +689,12 @@ static void usage(void)
            "-bsd type         select emulated BSD type FreeBSD/NetBSD/OpenBSD (default)\n"
            "\n"
            "Debug options:\n"
-           "-d options   activate log (default logfile=%s)\n"
-           "-D logfile   override default logfile location\n"
-           "-p pagesize  set the host page size to 'pagesize'\n"
-           "-singlestep  always run in singlestep mode\n"
-           "-strace      log system calls\n"
+           "-d item1[,...]    enable logging of specified items\n"
+           "                  (use '-d help' for a list of log items)\n"
+           "-D logfile        write logs to 'logfile' (default stderr)\n"
+           "-p pagesize       set the host page size to 'pagesize'\n"
+           "-singlestep       always run in singlestep mode\n"
+           "-strace           log system calls\n"
            "\n"
            "Environment variables:\n"
            "QEMU_STRACE       Print system calls and arguments similar to the\n"
@@ -709,8 +708,7 @@ static void usage(void)
            ,
            TARGET_ARCH,
            interp_prefix,
-           x86_stack_size,
-           DEBUG_LOGFILE);
+           x86_stack_size);
     exit(1);
 }
 
@@ -733,7 +731,7 @@ int main(int argc, char **argv)
 {
     const char *filename;
     const char *cpu_model;
-    const char *log_file = DEBUG_LOGFILE;
+    const char *log_file = NULL;
     const char *log_mask = NULL;
     struct target_pt_regs regs1, *regs = &regs1;
     struct image_info info1, *info = &info1;