[PATCH v2 0/2] Add efitextmode command

[PATCH v2 0/2] Add efitextmode command

[Glenn Washburn]

Updates since v1:
* Update documentation language as suggested by Paul

This patch add the efitextmode command which is used for showing all
available text output modes and setting a specific mode. Its basically the
equivalent of the EFI Shell's "mode" command and its output looks similar.
The main difference is that its shows the mode number in the listing and
takes a mode number when setting the mode. As a convenience, it can take
arguments "min" or "max" to set to the minimum or maximum mode.

Glenn

Glenn Washburn (2):
  efi: Add efitextmode command for getting/setting the text mode
    resolution
  docs: Document efitextmode command

 docs/grub.texi                       |  26 ++++++
 grub-core/Makefile.core.def          |   6 ++
 grub-core/commands/efi/efitextmode.c | 118 +++++++++++++++++++++++++++
 3 files changed, 150 insertions(+)
 create mode 100644 grub-core/commands/efi/efitextmode.c

-- 
2.34.1

[PATCH v2 1/2] efi: Add efitextmode command for getting/setting the text mode resolution

[Glenn Washburn]

This command is meant to behave similarly to the 'mode' command of the EFI
Shell application. One difference is that to set the mode the mode number
is given, not the rows and columns of the desired mode. Also supported are
the arguments "min" and "max", which set the mode to the minimum and
maximum mode respectively as calculated by the columns * rows of that mode.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Tested-by: Gerd Hoffmann <kraxel@redhat.com>
---
 grub-core/Makefile.core.def          |   6 ++
 grub-core/commands/efi/efitextmode.c | 118 +++++++++++++++++++++++++++
 2 files changed, 124 insertions(+)
 create mode 100644 grub-core/commands/efi/efitextmode.c

diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index 726f51be7..b22e48f0f 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -813,6 +813,12 @@ module = {
   enable = efi;
 };
 
+module = {
+  name = efitextmode;
+  efi = commands/efi/efitextmode.c;
+  enable = efi;
+};
+
 module = {
   name = blocklist;
   common = commands/blocklist.c;
diff --git a/grub-core/commands/efi/efitextmode.c b/grub-core/commands/efi/efitextmode.c
new file mode 100644
index 000000000..fb72aa6f3
--- /dev/null
+++ b/grub-core/commands/efi/efitextmode.c
@@ -0,0 +1,118 @@
+/* efitextmode.c - command to get/set text mode resolution */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2003,2005,2006,2007,2009  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/dl.h>
+#include <grub/misc.h>
+#include <grub/mm.h>
+#include <grub/command.h>
+#include <grub/i18n.h>
+#include <grub/efi/efi.h>
+#include <grub/efi/api.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+static grub_err_t
+grub_cmd_efitextmode (grub_command_t cmd __attribute__ ((unused)),
+		      int argc, char **args)
+{
+  grub_efi_simple_text_output_interface_t *o;
+  unsigned long mode;
+  const char *p = NULL;
+  grub_efi_status_t status;
+  grub_efi_uintn_t columns, rows;
+  grub_efi_int32_t i;
+
+  if (argc > 1)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("at most one argument expected"));
+
+  o = grub_efi_system_table->con_out;
+
+  if (argc == 1)
+    {
+      if (grub_strcmp (args[0], "min") == 0)
+	mode = 0;
+      else if (grub_strcmp (args[0], "max") == 0)
+	mode = o->mode->max_mode - 1;
+      else
+	{
+	  mode = grub_strtoul (args[0], &p, 0);
+
+	  if (grub_errno != GRUB_ERR_NONE)
+	    return grub_errno;
+
+	  if (*args[0] == '\0' || *p != '\0')
+	    return grub_error (GRUB_ERR_BAD_ARGUMENT,
+			       N_("non-numeric or invalid mode `%s'"),
+			       args[0]);
+	}
+
+      if (mode < (unsigned long) o->mode->max_mode)
+	{
+	  if (mode != (unsigned long) o->mode->mode)
+	    {
+	      status = efi_call_2 (o->set_mode, o, (grub_efi_int32_t) mode);
+	      if (status == GRUB_EFI_SUCCESS)
+		;
+	      else if (status == GRUB_EFI_DEVICE_ERROR)
+		return grub_error (GRUB_ERR_BAD_DEVICE,
+				   N_("device error: could not set requested"
+				      " mode"));
+	      else if (status == GRUB_EFI_UNSUPPORTED)
+		return grub_error (GRUB_ERR_OUT_OF_RANGE,
+				   N_("invalid mode: number not valid"));
+	      else
+		return grub_error (GRUB_ERR_BAD_OS,
+				   N_("unexpected EFI error number: `%u'"),
+				   (unsigned) status);
+	    }
+	}
+      else
+	return grub_error (GRUB_ERR_BAD_ARGUMENT,
+			   N_("invalid mode: `%lu' is greater than maximum"
+			      " mode `%lu'"),
+			   mode, (unsigned long) o->mode->max_mode);
+    }
+
+  if (argc == 0)
+    {
+      grub_printf_ (N_("Available modes for console output device.\n"));
+
+      for (i=0; i < o->mode->max_mode; i++)
+	if (GRUB_EFI_SUCCESS == efi_call_4 (o->query_mode, o, i,
+					    &columns, &rows))
+	  grub_printf_ (N_(" [%lu]  Col %5u Row %5u %c\n"),
+			(unsigned long) i, (unsigned) columns, (unsigned) rows,
+			(i == o->mode->mode) ? '*' : ' ');
+    }
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_command_t cmd;
+\f
+GRUB_MOD_INIT(cmp)
+{
+  cmd = grub_register_command ("efitextmode", grub_cmd_efitextmode,
+			       N_("[min|max|mode_num]"), N_("Get or set EFI text mode."));
+}
+
+GRUB_MOD_FINI(cmp)
+{
+  grub_unregister_command (cmd);
+}
-- 
2.34.1

Re: [PATCH v2 1/2] efi: Add efitextmode command for getting/setting the text mode resolution

[Daniel Kiper]

On Fri, May 13, 2022 at 12:54:11PM -0500, Glenn Washburn wrote:
> This command is meant to behave similarly to the 'mode' command of the EFI
> Shell application. One difference is that to set the mode the mode number
> is given, not the rows and columns of the desired mode. Also supported are
> the arguments "min" and "max", which set the mode to the minimum and
> maximum mode respectively as calculated by the columns * rows of that mode.
>
> Signed-off-by: Glenn Washburn <development@efficientek.com>
> Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
> Tested-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  grub-core/Makefile.core.def          |   6 ++
>  grub-core/commands/efi/efitextmode.c | 118 +++++++++++++++++++++++++++
>  2 files changed, 124 insertions(+)
>  create mode 100644 grub-core/commands/efi/efitextmode.c
>
> diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
> index 726f51be7..b22e48f0f 100644
> --- a/grub-core/Makefile.core.def
> +++ b/grub-core/Makefile.core.def
> @@ -813,6 +813,12 @@ module = {
>    enable = efi;
>  };
>
> +module = {
> +  name = efitextmode;
> +  efi = commands/efi/efitextmode.c;
> +  enable = efi;
> +};
> +
>  module = {
>    name = blocklist;
>    common = commands/blocklist.c;
> diff --git a/grub-core/commands/efi/efitextmode.c b/grub-core/commands/efi/efitextmode.c
> new file mode 100644
> index 000000000..fb72aa6f3
> --- /dev/null
> +++ b/grub-core/commands/efi/efitextmode.c
> @@ -0,0 +1,118 @@
> +/* efitextmode.c - command to get/set text mode resolution */
> +/*
> + *  GRUB  --  GRand Unified Bootloader
> + *  Copyright (C) 2003,2005,2006,2007,2009  Free Software Foundation, Inc.

s/2003,2005,2006,2007,2009/2022/

> + *  GRUB is free software: you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation, either version 3 of the License, or
> + *  (at your option) any later version.
> + *
> + *  GRUB is distributed in the hope that it will be useful,
> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + *  GNU General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.

Please add one line here describing what this module does. Good example
is in grub-core/kern/efi/sb.c.

> + */
> +
> +#include <grub/dl.h>
> +#include <grub/misc.h>
> +#include <grub/mm.h>
> +#include <grub/command.h>
> +#include <grub/i18n.h>
> +#include <grub/efi/efi.h>
> +#include <grub/efi/api.h>
> +
> +GRUB_MOD_LICENSE ("GPLv3+");
> +
> +static grub_err_t
> +grub_cmd_efitextmode (grub_command_t cmd __attribute__ ((unused)),
> +		      int argc, char **args)
> +{
> +  grub_efi_simple_text_output_interface_t *o;
> +  unsigned long mode;
> +  const char *p = NULL;
> +  grub_efi_status_t status;
> +  grub_efi_uintn_t columns, rows;
> +  grub_efi_int32_t i;
> +
> +  if (argc > 1)
> +    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("at most one argument expected"));
> +
> +  o = grub_efi_system_table->con_out;

I think you can do it in definition above.

> +
> +  if (argc == 1)
> +    {
> +      if (grub_strcmp (args[0], "min") == 0)
> +	mode = 0;
> +      else if (grub_strcmp (args[0], "max") == 0)
> +	mode = o->mode->max_mode - 1;

Are your sure "o" and "o->mode" are always not NULL?

> +      else
> +	{
> +	  mode = grub_strtoul (args[0], &p, 0);
> +
> +	  if (grub_errno != GRUB_ERR_NONE)
> +	    return grub_errno;

Please drop this check. It is redundant as we chatted earlier.

> +	  if (*args[0] == '\0' || *p != '\0')
> +	    return grub_error (GRUB_ERR_BAD_ARGUMENT,
> +			       N_("non-numeric or invalid mode `%s'"),
> +			       args[0]);
> +	}
> +
> +      if (mode < (unsigned long) o->mode->max_mode)
> +	{
> +	  if (mode != (unsigned long) o->mode->mode)
> +	    {
> +	      status = efi_call_2 (o->set_mode, o, (grub_efi_int32_t) mode);
> +	      if (status == GRUB_EFI_SUCCESS)
> +		;
> +	      else if (status == GRUB_EFI_DEVICE_ERROR)
> +		return grub_error (GRUB_ERR_BAD_DEVICE,
> +				   N_("device error: could not set requested"
> +				      " mode"));

Please do not wrap error msg here. I am OK with lines a bit longer than
80 chars. And I think you can put args[0] in one line with error msg
above too.

> +	      else if (status == GRUB_EFI_UNSUPPORTED)
> +		return grub_error (GRUB_ERR_OUT_OF_RANGE,
> +				   N_("invalid mode: number not valid"));
> +	      else
> +		return grub_error (GRUB_ERR_BAD_OS,
> +				   N_("unexpected EFI error number: `%u'"),
> +				   (unsigned) status);
> +	    }
> +	}
> +      else
> +	return grub_error (GRUB_ERR_BAD_ARGUMENT,
> +			   N_("invalid mode: `%lu' is greater than maximum"
> +			      " mode `%lu'"),

Ditto.

> +			   mode, (unsigned long) o->mode->max_mode);
> +    }
> +
> +  if (argc == 0)
> +    {
> +      grub_printf_ (N_("Available modes for console output device.\n"));
> +
> +      for (i=0; i < o->mode->max_mode; i++)

i = 0; Missing spaces...

> +	if (GRUB_EFI_SUCCESS == efi_call_4 (o->query_mode, o, i,
> +					    &columns, &rows))
> +	  grub_printf_ (N_(" [%lu]  Col %5u Row %5u %c\n"),
> +			(unsigned long) i, (unsigned) columns, (unsigned) rows,

Could we avoid this casts? Same above. I think we can introduce
PRIxGRUB_EFI_UINT32_T, etc. They should land in include/grub/efi/api.h
somewhere around grub_efi_uint*_t typedefs.

> +			(i == o->mode->mode) ? '*' : ' ');
> +    }
> +
> +  return GRUB_ERR_NONE;
> +}
> +
> +static grub_command_t cmd;
> +\f

Please drop this ^L.

> +GRUB_MOD_INIT(cmp)

GRUB_MOD_INIT (cmp)
> +{
> +  cmd = grub_register_command ("efitextmode", grub_cmd_efitextmode,
> +			       N_("[min|max|mode_num]"), N_("Get or set EFI text mode."));
> +}
> +
> +GRUB_MOD_FINI(cmp)

GRUB_MOD_FINI (cmp)

> +{
> +  grub_unregister_command (cmd);
> +}

Daniel

[PATCH v2 2/2] docs: Document efitextmode command

[Glenn Washburn]

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 docs/grub.texi | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/docs/grub.texi b/docs/grub.texi
index 5de94d062..178957096 100644
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -4049,6 +4049,7 @@ you forget a command, you can run the command @command{help}
 * distrust::                    Remove a pubkey from trusted keys
 * drivemap::                    Map a drive to another
 * echo::                        Display a line of text
+* efitextmode::                 Set/Get text output mode resolution
 * eval::                        Evaluate agruments as GRUB commands
 * export::                      Export an environment variable
 * false::                       Do nothing, unsuccessfully
@@ -4505,6 +4506,31 @@ character will print that character.
 @end deffn
 
 
+@node efitextmode
+@subsection efitextmode
+
+@deffn Command efitextmode [min | max | mode_num]
+When used with no arguments displays all available text output modes. The
+set mode determines the columns and rows of the text display when in
+text mode. An asterisk, @samp{*}, will be at the end of the line of the
+currently set mode.
+
+Otherwise the command only takes a single parameter, which can be
+@samp{min}, @samp{max}, or a mode number given by the listing when run
+with no arguments. These arguments set the mode to the minimum, maximum,
+and particular mode respectively.
+
+By default GRUB will start in whatever mode the EFI firmware defaults to.
+There are firmwares known to set up the default mode such that output
+behaves strangely, for example the cursor in the grub shell never reaches
+the bottom of the screen or, when typing characters at the prompt,
+characters from previous command output are overwritten. Setting the mode
+may fix this.
+
+Note: This command is only available on EFI platforms.
+@end deffn
+
+
 @node eval
 @subsection eval
 
-- 
2.34.1

Re: [PATCH v2 2/2] docs: Document efitextmode command

[Daniel Kiper]

On Fri, May 13, 2022 at 12:54:12PM -0500, Glenn Washburn wrote:
> Signed-off-by: Glenn Washburn <development@efficientek.com>

I think this patch should be merged with patch #1.

> ---
>  docs/grub.texi | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/docs/grub.texi b/docs/grub.texi
> index 5de94d062..178957096 100644
> --- a/docs/grub.texi
> +++ b/docs/grub.texi
> @@ -4049,6 +4049,7 @@ you forget a command, you can run the command @command{help}
>  * distrust::                    Remove a pubkey from trusted keys
>  * drivemap::                    Map a drive to another
>  * echo::                        Display a line of text
> +* efitextmode::                 Set/Get text output mode resolution
>  * eval::                        Evaluate agruments as GRUB commands
>  * export::                      Export an environment variable
>  * false::                       Do nothing, unsuccessfully
> @@ -4505,6 +4506,31 @@ character will print that character.
>  @end deffn
>
>
> +@node efitextmode
> +@subsection efitextmode
> +
> +@deffn Command efitextmode [min | max | mode_num]

s/mode_num/<mode_num>/?

After some thinking it seems to me this interface is not very convenient.
My guess is that the same mode may have different <mode_num> on
different implementations/platforms. I think EFI shell "mode" command
"col" "row" approach is more universal/reliable. Though I think it makes
sense to leave min and max as is...

> +When used with no arguments displays all available text output modes. The
> +set mode determines the columns and rows of the text display when in
> +text mode. An asterisk, @samp{*}, will be at the end of the line of the
> +currently set mode.
> +
> +Otherwise the command only takes a single parameter, which can be
> +@samp{min}, @samp{max}, or a mode number given by the listing when run
> +with no arguments. These arguments set the mode to the minimum, maximum,
> +and particular mode respectively.
> +
> +By default GRUB will start in whatever mode the EFI firmware defaults to.
> +There are firmwares known to set up the default mode such that output
> +behaves strangely, for example the cursor in the grub shell never reaches
> +the bottom of the screen or, when typing characters at the prompt,
> +characters from previous command output are overwritten. Setting the mode
> +may fix this.
> +
> +Note: This command is only available on EFI platforms.

s/./ and is similar to EFI shell "mode" command./?

Daniel

Re: [PATCH v2 2/2] docs: Document efitextmode command

[Glenn Washburn]

On Tue, 5 Jul 2022 16:01:04 +0200
Daniel Kiper <dkiper@net-space.pl> wrote:

> On Fri, May 13, 2022 at 12:54:12PM -0500, Glenn Washburn wrote:
> > Signed-off-by: Glenn Washburn <development@efficientek.com>
> 
> I think this patch should be merged with patch #1.
> 
> > ---
> >  docs/grub.texi | 26 ++++++++++++++++++++++++++
> >  1 file changed, 26 insertions(+)
> >
> > diff --git a/docs/grub.texi b/docs/grub.texi
> > index 5de94d062..178957096 100644
> > --- a/docs/grub.texi
> > +++ b/docs/grub.texi
> > @@ -4049,6 +4049,7 @@ you forget a command, you can run the command @command{help}
> >  * distrust::                    Remove a pubkey from trusted keys
> >  * drivemap::                    Map a drive to another
> >  * echo::                        Display a line of text
> > +* efitextmode::                 Set/Get text output mode resolution
> >  * eval::                        Evaluate agruments as GRUB commands
> >  * export::                      Export an environment variable
> >  * false::                       Do nothing, unsuccessfully
> > @@ -4505,6 +4506,31 @@ character will print that character.
> >  @end deffn
> >
> >
> > +@node efitextmode
> > +@subsection efitextmode
> > +
> > +@deffn Command efitextmode [min | max | mode_num]
> 
> s/mode_num/<mode_num>/?
> 
> After some thinking it seems to me this interface is not very convenient.
> My guess is that the same mode may have different <mode_num> on
> different implementations/platforms. I think EFI shell "mode" command
> "col" "row" approach is more universal/reliable. Though I think it makes
> sense to leave min and max as is...

Hmm, not convenient for who? in what scenario? Its more convenient for
someone at a grub prompt and wanting to set the mode (type less numbers
and when switching between modes easier to go to the next higher or
lower mode). It was more convenient for someone to remember which mode
they wanted when they want to put it in a grub config, which can take a
while because the OS generally needs to boot to edit the config.

The only way I can see specifying cols and rows as convenient is for
someone who wants to make sure that they are at a specific textmode
resolution. But what is the use case for that? Its also convenient for
someone reading a grub config file and wanting to know what resolution
is being requested (which may not be the resolution you get, if its not
supported). But again, who needs to do that? And this can be remedied
by a comment in the config file if desired.

How about keeping the mode number usage if one argument is supplied and
adding the cols/rows usage when two numbers are supplied?

Glenn

> > +When used with no arguments displays all available text output modes. The
> > +set mode determines the columns and rows of the text display when in
> > +text mode. An asterisk, @samp{*}, will be at the end of the line of the
> > +currently set mode.
> > +
> > +Otherwise the command only takes a single parameter, which can be
> > +@samp{min}, @samp{max}, or a mode number given by the listing when run
> > +with no arguments. These arguments set the mode to the minimum, maximum,
> > +and particular mode respectively.
> > +
> > +By default GRUB will start in whatever mode the EFI firmware defaults to.
> > +There are firmwares known to set up the default mode such that output
> > +behaves strangely, for example the cursor in the grub shell never reaches
> > +the bottom of the screen or, when typing characters at the prompt,
> > +characters from previous command output are overwritten. Setting the mode
> > +may fix this.
> > +
> > +Note: This command is only available on EFI platforms.
> 
> s/./ and is similar to EFI shell "mode" command./?
> 
> Daniel

Re: [PATCH v2 2/2] docs: Document efitextmode command

[Daniel Kiper]

On Fri, Jul 08, 2022 at 07:29:51PM -0500, Glenn Washburn wrote:
> On Tue, 5 Jul 2022 16:01:04 +0200
> Daniel Kiper <dkiper@net-space.pl> wrote:
>
> > On Fri, May 13, 2022 at 12:54:12PM -0500, Glenn Washburn wrote:
> > > Signed-off-by: Glenn Washburn <development@efficientek.com>
> >
> > I think this patch should be merged with patch #1.
> >
> > > ---
> > >  docs/grub.texi | 26 ++++++++++++++++++++++++++
> > >  1 file changed, 26 insertions(+)
> > >
> > > diff --git a/docs/grub.texi b/docs/grub.texi
> > > index 5de94d062..178957096 100644
> > > --- a/docs/grub.texi
> > > +++ b/docs/grub.texi
> > > @@ -4049,6 +4049,7 @@ you forget a command, you can run the command @command{help}
> > >  * distrust::                    Remove a pubkey from trusted keys
> > >  * drivemap::                    Map a drive to another
> > >  * echo::                        Display a line of text
> > > +* efitextmode::                 Set/Get text output mode resolution
> > >  * eval::                        Evaluate agruments as GRUB commands
> > >  * export::                      Export an environment variable
> > >  * false::                       Do nothing, unsuccessfully
> > > @@ -4505,6 +4506,31 @@ character will print that character.
> > >  @end deffn
> > >
> > >
> > > +@node efitextmode
> > > +@subsection efitextmode
> > > +
> > > +@deffn Command efitextmode [min | max | mode_num]
> >
> > s/mode_num/<mode_num>/?
> >
> > After some thinking it seems to me this interface is not very convenient.
> > My guess is that the same mode may have different <mode_num> on
> > different implementations/platforms. I think EFI shell "mode" command
> > "col" "row" approach is more universal/reliable. Though I think it makes
> > sense to leave min and max as is...
>
> Hmm, not convenient for who? in what scenario? Its more convenient for
> someone at a grub prompt and wanting to set the mode (type less numbers
> and when switching between modes easier to go to the next higher or
> lower mode). It was more convenient for someone to remember which mode
> they wanted when they want to put it in a grub config, which can take a
> while because the OS generally needs to boot to edit the config.
>
> The only way I can see specifying cols and rows as convenient is for
> someone who wants to make sure that they are at a specific textmode
> resolution. But what is the use case for that? Its also convenient for
> someone reading a grub config file and wanting to know what resolution
> is being requested (which may not be the resolution you get, if its not
> supported). But again, who needs to do that? And this can be remedied
> by a comment in the config file if desired.

There is no guarantee the mode at index A is BxC across all machines.
So, if somebody wants mode BxC on every machine then they should have
a chance to specify it explicitly using "col" "row" arguments.

> How about keeping the mode number usage if one argument is supplied and
> adding the cols/rows usage when two numbers are supplied?

I am OK with it. However, please add a note to the docs saying nobody
can rely on that an index A corresponds to BxC mode on every machine or
something like that.

Daniel