xl: Add subcommand 'xl dmesg'

xl: Add subcommand 'xl dmesg'

[Yu Zhiguo]

Can be used to read and/or clear dmesg buffer.

Signed-off-by: Yu Zhiguo <yuzg@cn.fujitsu.com>

diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/libxl.c
--- a/tools/libxl/libxl.c	Wed May 19 22:59:52 2010 +0100
+++ b/tools/libxl/libxl.c	Thu May 20 19:52:13 2010 +0800
@@ -2827,6 +2827,18 @@
     return xc_send_debug_keys(ctx->xch, keys);
 }
 
+int libxl_readconsolering(struct libxl_ctx *ctx, char **pbuffer,
+                          unsigned int *pnr_chars, int clear,
+                          int incremental, uint32_t *pindex)
+{
+    int ret;
+
+    ret = xc_readconsolering(ctx->xch, pbuffer, pnr_chars, clear,
+                             incremental, pindex);
+
+    return ret;
+}
+
 uint32_t libxl_vm_get_start_time(struct libxl_ctx *ctx, uint32_t domid)
 {
     char *dompath = libxl_xs_get_dompath(ctx, domid);
diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/libxl.h
--- a/tools/libxl/libxl.h	Wed May 19 22:59:52 2010 +0100
+++ b/tools/libxl/libxl.h	Thu May 20 19:52:13 2010 +0800
@@ -512,6 +512,9 @@
                        char *trigger_name, uint32_t vcpuid);
 int libxl_send_sysrq(struct libxl_ctx *ctx, uint32_t domid, char sysrq);
 int libxl_send_debug_keys(struct libxl_ctx *ctx, char *keys);
+int libxl_readconsolering(struct libxl_ctx *ctx, char **pbuffer,
+                          unsigned int *pnr_chars, int clear,
+                          int incremental, uint32_t *pindex);
 uint32_t libxl_vm_get_start_time(struct libxl_ctx *ctx, uint32_t domid);
 
 char *libxl_tmem_list(struct libxl_ctx *ctx, uint32_t domid, int use_long);
diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c	Wed May 19 22:59:52 2010 +0100
+++ b/tools/libxl/xl_cmdimpl.c	Thu May 20 19:52:13 2010 +0800
@@ -3246,6 +3246,66 @@
     exit(0);
 }
 
+int main_dmesg(int argc, char **argv)
+{
+    unsigned int clear = 0, index = 0, incremental = 0;
+    unsigned int count = 16384 + 1, size = count;
+    char *str, *ptr;
+    int opt, ret;
+
+    while ((opt = getopt(argc, argv, "hc")) != -1) {
+        switch (opt) {
+        case 'c':
+            clear = 1;
+            break;
+        case 'h':
+            help("dmesg");
+            exit(0);
+        default:
+            fprintf(stderr, "option not supported\n");
+            break;
+        }
+    }
+
+    str = malloc(size);
+    memset(str, 0, size);
+    ret = libxl_readconsolering(&ctx, &str, &count, clear,
+                                incremental, &index);
+    if (ret < 0)
+        goto out;
+
+    while (!incremental && count == size) {
+        size += count - 1;
+        if (size < count)
+            break;
+
+        ptr = realloc(str, size);
+        if (!ptr)
+            break;
+
+        str = ptr + count;
+        count = size - count;
+        ret = libxl_readconsolering(&ctx, &str, &count, clear,
+                                    1, &index);
+        if (ret < 0) {
+            str = ptr;
+            break;
+        }
+
+        count += str - ptr;
+        str = ptr;
+    }
+
+out:
+    printf(str);
+    free(str);
+
+    if (ret)
+        exit(1);
+
+    exit(0);
+}
+
 int main_top(int argc, char **argv)
 {
     int opt;
diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/xl_cmdimpl.h
--- a/tools/libxl/xl_cmdimpl.h	Wed May 19 22:59:52 2010 +0100
+++ b/tools/libxl/xl_cmdimpl.h	Thu May 20 19:52:13 2010 +0800
@@ -45,6 +45,7 @@
 int main_trigger(int argc, char **argv);
 int main_sysrq(int argc, char **argv);
 int main_debug_keys(int argc, char **argv);
+int main_dmesg(int argc, char **argv);
 int main_top(int argc, char **argv);
 int main_networkattach(int argc, char **argv);
 int main_networklist(int argc, char **argv);
diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/xl_cmdtable.c
--- a/tools/libxl/xl_cmdtable.c	Wed May 19 22:59:52 2010 +0100
+++ b/tools/libxl/xl_cmdtable.c	Thu May 20 19:52:13 2010 +0800
@@ -191,6 +191,12 @@
       "Send debug keys to Xen",
       "<Keys>",
     },
+    { "dmesg",
+      &main_dmesg,
+      "Read and/or clear dmesg buffer",
+      "[-c]",
+      "  -c                        Clear dmesg buffer as well as printing it",
+    },
     { "top",
       &main_top,
       "Monitor a host and the domains in real time",

Re: xl: Add subcommand 'xl dmesg'

[Stefano Stabellini]

On Thu, 20 May 2010, Yu Zhiguo wrote:
> Can be used to read and/or clear dmesg buffer.
> 

Thanks for the patch!

The implementation is good, but I think we could probably offer an
higher level API in libxenlight than just a wrapper around
xc_readconsolering.
I think we should have a libxl_dmesg instead of libxl_readconsolering,
and libxl_dmesg would print dmesg itself using the libxl logging
functions.
The caller can setup the logging function so that dmesg is printed to
stdout in this case.


> Signed-off-by: Yu Zhiguo <yuzg@cn.fujitsu.com>
> 
> diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/libxl.c
> --- a/tools/libxl/libxl.c	Wed May 19 22:59:52 2010 +0100
> +++ b/tools/libxl/libxl.c	Thu May 20 19:52:13 2010 +0800
> @@ -2827,6 +2827,18 @@
>      return xc_send_debug_keys(ctx->xch, keys);
>  }
>  
> +int libxl_readconsolering(struct libxl_ctx *ctx, char **pbuffer,
> +                          unsigned int *pnr_chars, int clear,
> +                          int incremental, uint32_t *pindex)
> +{
> +    int ret;
> +
> +    ret = xc_readconsolering(ctx->xch, pbuffer, pnr_chars, clear,
> +                             incremental, pindex);
> +
> +    return ret;
> +}
> +
>  uint32_t libxl_vm_get_start_time(struct libxl_ctx *ctx, uint32_t domid)
>  {
>      char *dompath = libxl_xs_get_dompath(ctx, domid);
> diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/libxl.h
> --- a/tools/libxl/libxl.h	Wed May 19 22:59:52 2010 +0100
> +++ b/tools/libxl/libxl.h	Thu May 20 19:52:13 2010 +0800
> @@ -512,6 +512,9 @@
>                         char *trigger_name, uint32_t vcpuid);
>  int libxl_send_sysrq(struct libxl_ctx *ctx, uint32_t domid, char sysrq);
>  int libxl_send_debug_keys(struct libxl_ctx *ctx, char *keys);
> +int libxl_readconsolering(struct libxl_ctx *ctx, char **pbuffer,
> +                          unsigned int *pnr_chars, int clear,
> +                          int incremental, uint32_t *pindex);
>  uint32_t libxl_vm_get_start_time(struct libxl_ctx *ctx, uint32_t domid);
>  
>  char *libxl_tmem_list(struct libxl_ctx *ctx, uint32_t domid, int use_long);
> diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/xl_cmdimpl.c
> --- a/tools/libxl/xl_cmdimpl.c	Wed May 19 22:59:52 2010 +0100
> +++ b/tools/libxl/xl_cmdimpl.c	Thu May 20 19:52:13 2010 +0800
> @@ -3246,6 +3246,66 @@
>      exit(0);
>  }
>  
> +int main_dmesg(int argc, char **argv)
> +{
> +    unsigned int clear = 0, index = 0, incremental = 0;
> +    unsigned int count = 16384 + 1, size = count;
> +    char *str, *ptr;
> +    int opt, ret;
> +
> +    while ((opt = getopt(argc, argv, "hc")) != -1) {
> +        switch (opt) {
> +        case 'c':
> +            clear = 1;
> +            break;
> +        case 'h':
> +            help("dmesg");
> +            exit(0);
> +        default:
> +            fprintf(stderr, "option not supported\n");
> +            break;
> +        }
> +    }
> +
> +    str = malloc(size);
> +    memset(str, 0, size);
> +    ret = libxl_readconsolering(&ctx, &str, &count, clear,
> +                                incremental, &index);
> +    if (ret < 0)
> +        goto out;
> +
> +    while (!incremental && count == size) {
> +        size += count - 1;
> +        if (size < count)
> +            break;
> +
> +        ptr = realloc(str, size);
> +        if (!ptr)
> +            break;
> +
> +        str = ptr + count;
> +        count = size - count;
> +        ret = libxl_readconsolering(&ctx, &str, &count, clear,
> +                                    1, &index);
> +        if (ret < 0) {
> +            str = ptr;
> +            break;
> +        }
> +
> +        count += str - ptr;
> +        str = ptr;
> +    }
> +
> +out:
> +    printf(str);
> +    free(str);
> +
> +    if (ret)
> +        exit(1);
> +
> +    exit(0);
> +}
> +
>  int main_top(int argc, char **argv)
>  {
>      int opt;
> diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/xl_cmdimpl.h
> --- a/tools/libxl/xl_cmdimpl.h	Wed May 19 22:59:52 2010 +0100
> +++ b/tools/libxl/xl_cmdimpl.h	Thu May 20 19:52:13 2010 +0800
> @@ -45,6 +45,7 @@
>  int main_trigger(int argc, char **argv);
>  int main_sysrq(int argc, char **argv);
>  int main_debug_keys(int argc, char **argv);
> +int main_dmesg(int argc, char **argv);
>  int main_top(int argc, char **argv);
>  int main_networkattach(int argc, char **argv);
>  int main_networklist(int argc, char **argv);
> diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/xl_cmdtable.c
> --- a/tools/libxl/xl_cmdtable.c	Wed May 19 22:59:52 2010 +0100
> +++ b/tools/libxl/xl_cmdtable.c	Thu May 20 19:52:13 2010 +0800
> @@ -191,6 +191,12 @@
>        "Send debug keys to Xen",
>        "<Keys>",
>      },
> +    { "dmesg",
> +      &main_dmesg,
> +      "Read and/or clear dmesg buffer",
> +      "[-c]",
> +      "  -c                        Clear dmesg buffer as well as printing it",
> +    },
>      { "top",
>        &main_top,
>        "Monitor a host and the domains in real time",
> 

Re: xl: Add subcommand 'xl dmesg'

[Ian Jackson]

Stefano Stabellini writes ("[Xen-devel] Re: xl: Add subcommand 'xl dmesg'"):
> The implementation is good, but I think we could probably offer an
> higher level API in libxenlight than just a wrapper around
> xc_readconsolering.

I agree that a higher-level API would be good.

> I think we should have a libxl_dmesg instead of libxl_readconsolering,
> and libxl_dmesg would print dmesg itself using the libxl logging
> functions.
> The caller can setup the logging function so that dmesg is printed to
> stdout in this case.

Are we sure that calling the logging function for every line in the
ring is really what we want ?  If nothing else this will repeat
messages.

Ian.

Re: xl: Add subcommand 'xl dmesg'

[Ian Jackson]

Ian Jackson writes ("[Xen-devel] Re: xl: Add subcommand 'xl dmesg'"):
> Are we sure that calling the logging function for every line in the
> ring is really what we want ?  If nothing else this will repeat
> messages.

Having thought about this some more (and had a chat with Stefano) I
think the right libxl interface is an iterator, something like this:

 struct libxl_xen_console_reader*
 libxl_xen_console_read_start(struct libxl_ctx*);

 int
 libxl_xen_console_read_line(struct libxl_ctx*,
                             struct libxl_xen_console_reader*,
                             char **line_r);
   /* return values:                                          *line_r
    *   1          success, whole line obtained from buffer    non-0
    *   0          no more lines available right now           0
    *   negative   error code ERROR_*                          0
    * On success *line_r is updated to point to a nul-terminated
    * string which is valid until the next call on the same console
    * reader.  The libxl caller may overwrite parts of the string
    * if it wishes. */

 void
 libxl_xen_console_read_finish(struct libxl_ctx*,
                               struct libxl_xen_console_reader*);

"xl dmesg" then calls _start, loops calling line, and then calls
_finish.  Other libxl callers can plumb it into logging or poll for
more output of whatever they like.

Ian.

Re: Re: xl: Add subcommand 'xl dmesg'

[Yu Zhiguo]

Hi Ian,

Ian Jackson wrote:
> 
> Having thought about this some more (and had a chat with Stefano) I
> think the right libxl interface is an iterator, something like this:
> 

Thanks for your explanation, I'll fix it later.


Regards
Yu Zhiguo

Re: Re: xl: Add subcommand 'xl dmesg'

[Yu Zhiguo]

Hi Ian,

Yu Zhiguo wrote:
> Ian Jackson wrote:
>> Having thought about this some more (and had a chat with Stefano) I
>> think the right libxl interface is an iterator, something like this:
>>
> 

Fix it to an iterator now, how about this version.

-----------------------

Can be used to read and/or clear dmesg buffer.

Signed-off-by: Yu Zhiguo <yuzg@cn.fujitsu.com>

diff -r 93410e5e4ad8 -r 2302edf6155c tools/libxl/libxl.c
--- a/tools/libxl/libxl.c	Sat May 22 06:36:41 2010 +0100
+++ b/tools/libxl/libxl.c	Wed May 26 00:09:54 2010 +0800
@@ -2827,6 +2827,72 @@
     return xc_send_debug_keys(ctx->xch, keys);
 }
 
+struct libxl_xen_console_reader *
+    libxl_xen_console_read_start(struct libxl_ctx *ctx, int clear)
+{
+    struct libxl_xen_console_reader *cr;
+    unsigned int size = 16384;
+    char *buf = malloc(size);
+
+    if (!buf) {
+        XL_LOG_ERRNO(ctx, XL_LOG_ERROR, "cannot malloc buffer for libxl_xen_console_reader,"
+            " size is %u", size);
+        return NULL;
+    }
+
+    cr = malloc(sizeof(struct libxl_xen_console_reader));
+    if (!cr) {
+        XL_LOG_ERRNO(ctx, XL_LOG_ERROR, "cannot malloc libxl_xen_console_reader");
+        return NULL;
+    }
+
+    memset(cr, 0, sizeof(struct libxl_xen_console_reader));
+    cr->buffer = buf;
+    cr->size = size;
+    cr->count = size;
+    cr->clear = clear;
+    cr->incremental = 1;
+
+    return cr;
+}
+
+/* return values:                                          *line_r
+ *   1          success, whole line obtained from buffer    non-0
+ *   0          no more lines available right now           0
+ *   negative   error code ERROR_*                          0
+ * On success *line_r is updated to point to a nul-terminated
+ * string which is valid until the next call on the same console
+ * reader.  The libxl caller may overwrite parts of the string
+ * if it wishes. */
+int libxl_xen_console_read_line(struct libxl_ctx *ctx,
+                                struct libxl_xen_console_reader *cr,
+                                char **line_r)
+{
+    int ret;
+
+    memset(cr->buffer, 0, cr->size);
+    ret = xc_readconsolering(ctx->xch, &cr->buffer, &cr->count,
+                             cr->clear, cr->incremental, &cr->index);
+    if (!ret) {
+        if (cr->count) {
+            *line_r = cr->buffer;
+            ret = 1;
+        } else {
+            *line_r = NULL;
+            ret = 0;
+        }
+    }
+
+    return ret;
+}
+
+void libxl_xen_console_read_finish(struct libxl_ctx *ctx,
+                                   struct libxl_xen_console_reader *cr)
+{
+    free(cr->buffer);
+    free(cr);
+}
+
 uint32_t libxl_vm_get_start_time(struct libxl_ctx *ctx, uint32_t domid)
 {
     char *dompath = libxl_xs_get_dompath(ctx, domid);
diff -r 93410e5e4ad8 -r 2302edf6155c tools/libxl/libxl.h
--- a/tools/libxl/libxl.h	Sat May 22 06:36:41 2010 +0100
+++ b/tools/libxl/libxl.h	Wed May 26 00:09:54 2010 +0800
@@ -512,6 +512,24 @@
                        char *trigger_name, uint32_t vcpuid);
 int libxl_send_sysrq(struct libxl_ctx *ctx, uint32_t domid, char sysrq);
 int libxl_send_debug_keys(struct libxl_ctx *ctx, char *keys);
+
+struct libxl_xen_console_reader {
+    char *buffer;
+    unsigned int size;
+    unsigned int count;
+    unsigned int clear;
+    unsigned int incremental;
+    unsigned int index;
+};
+
+struct libxl_xen_console_reader *
+    libxl_xen_console_read_start(struct libxl_ctx *ctx, int clear);
+int libxl_xen_console_read_line(struct libxl_ctx *ctx,
+                                struct libxl_xen_console_reader *cr,
+                                char **line_r);
+void libxl_xen_console_read_finish(struct libxl_ctx *ctx,
+                                   struct libxl_xen_console_reader *cr);
+
 uint32_t libxl_vm_get_start_time(struct libxl_ctx *ctx, uint32_t domid);
 
 char *libxl_tmem_list(struct libxl_ctx *ctx, uint32_t domid, int use_long);
diff -r 93410e5e4ad8 -r 2302edf6155c tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c	Sat May 22 06:36:41 2010 +0100
+++ b/tools/libxl/xl_cmdimpl.c	Wed May 26 00:09:54 2010 +0800
@@ -3246,6 +3246,44 @@
     exit(0);
 }
 
+int main_dmesg(int argc, char **argv)
+{
+    unsigned int clear = 0;
+    struct libxl_xen_console_reader *cr;
+    char *line;
+    int opt, ret = 1;
+
+    while ((opt = getopt(argc, argv, "hc")) != -1) {
+        switch (opt) {
+        case 'c':
+            clear = 1;
+            break;
+        case 'h':
+            help("dmesg");
+            exit(0);
+        default:
+            fprintf(stderr, "option not supported\n");
+            break;
+        }
+    }
+
+    cr = libxl_xen_console_read_start(&ctx, clear);
+    if (!cr)
+        goto finish;
+
+    while (1) {
+        ret = libxl_xen_console_read_line(&ctx, cr, &line);
+        if (ret > 0)
+            printf(line);
+        else
+            break;
+    }
+
+finish:
+    libxl_xen_console_read_finish(&ctx, cr);
+    exit(ret);
+}
+
 int main_top(int argc, char **argv)
 {
     int opt;
diff -r 93410e5e4ad8 -r 2302edf6155c tools/libxl/xl_cmdimpl.h
--- a/tools/libxl/xl_cmdimpl.h	Sat May 22 06:36:41 2010 +0100
+++ b/tools/libxl/xl_cmdimpl.h	Wed May 26 00:09:54 2010 +0800
@@ -45,6 +45,7 @@
 int main_trigger(int argc, char **argv);
 int main_sysrq(int argc, char **argv);
 int main_debug_keys(int argc, char **argv);
+int main_dmesg(int argc, char **argv);
 int main_top(int argc, char **argv);
 int main_networkattach(int argc, char **argv);
 int main_networklist(int argc, char **argv);
diff -r 93410e5e4ad8 -r 2302edf6155c tools/libxl/xl_cmdtable.c
--- a/tools/libxl/xl_cmdtable.c	Sat May 22 06:36:41 2010 +0100
+++ b/tools/libxl/xl_cmdtable.c	Wed May 26 00:09:54 2010 +0800
@@ -191,6 +191,12 @@
       "Send debug keys to Xen",
       "<Keys>",
     },
+    { "dmesg",
+      &main_dmesg,
+      "Read and/or clear dmesg buffer",
+      "[-c]",
+      "  -c                        Clear dmesg buffer as well as printing it",
+    },
     { "top",
       &main_top,
       "Monitor a host and the domains in real time",