[Xen-devel] [PATCH 2/3] tools/xenconsoled: Possibly perform repeated xc_readconsolering() hypercalls

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The size of the Xen console ring is runtime configurable, so the statically
sized 16k buffer is not necessarily sufficient.  Make repeated
xc_readconsolering() hypercalls while Xen managed to completely fill the
provided buffer.

Also, change the buffer to being static to save on stack space.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
---
 tools/console/daemon/io.c |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/console/daemon/io.c b/tools/console/daemon/io.c
index 313b256..b1268fa 100644
--- a/tools/console/daemon/io.c
+++ b/tools/console/daemon/io.c
@@ -909,17 +909,24 @@ static void handle_xs(void)
 
 static void handle_hv_logs(xc_evtchn *xce_handle)
 {
-       char buffer[1024*16];
+       static char buffer[1024*16];
        char *bufptr = buffer;
-       unsigned int size = sizeof(buffer);
+       unsigned int size;
        static uint32_t index = 0;
        evtchn_port_or_error_t port;
 
        if ((port = xc_evtchn_pending(xce_handle)) == -1)
                return;
 
-       if (xc_readconsolering(xc, bufptr, &size, 0, 1, &index) == 0 && size > 
0) {
+       do
+       {
                int logret;
+
+               size = sizeof(buffer);
+               if (xc_readconsolering(xc, bufptr, &size, 0, 1, &index) != 0 ||
+                   size == 0)
+                       break;
+
                if (log_time_hv)
                        logret = write_with_timestamp(log_hv_fd, buffer, size,
                                                      &log_time_hv_needts);
@@ -929,7 +936,7 @@ static void handle_hv_logs(xc_evtchn *xce_handle)
                if (logret < 0)
                        dolog(LOG_ERR, "Failed to write hypervisor log: "
                                       "%d (%s)", errno, strerror(errno));
-       }
+       } while (size == sizeof(buffer));
 
        (void)xc_evtchn_unmask(xce_handle, port);
 }
-- 
1.7.10.4


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