Re: libgloss/arm: monitor_stderr [PATCH]

[Jeff Johnston <jjohnstn at redhat dot com>]

Patch checked in.  Thanks.

-- Jeff J.

Shaun Jackman wrote:
> 2005/8/5, Nick Clifton <nickc@redhat.com>:
>
> > Assuming that nobody from the kernel world has a problem with this, then
> > I would have no problem recommending that Jeff accepts it - with one
> > proviso however:
>
> ... 
>
> > I think that you ought to add a comment to the code explaining the
> > situation (ie opening the same file name with different modes in order
> > to allow the kernel to choose whether to use one or two file
> > descriptors).  Otherwise future programmers might come along and think
> > that this is a bug.
> >
> > Cheers
> >   Nick
>
>
> I've added an explanatory comment.
>
> Cheers,
> Shaun
>
> 2005-08-04  Shaun Jackman  <sjackman@gmail.com>
>
> 	* libgloss/syscalls.c (initialise_monitor_handles): Set
> 	monitor_stderr to the result of SWI_open(":tt", "a")
> 	instead of simply duplicating stdout.
>
> Index: libgloss/arm/syscalls.c
> ===================================================================
> RCS file: /cvs/src/src/libgloss/arm/syscalls.c,v
> retrieving revision 1.6
> diff -u -r1.6 syscalls.c
> --- libgloss/arm/syscalls.c	2 Aug 2005 19:17:21 -0000	1.6
> +++ libgloss/arm/syscalls.c	15 Aug 2005 23:05:07 -0000
> @@ -133,6 +133,16 @@
>  {
>    int i;
>    
> +  /* Open the standard file descriptors by opening the special
> +   * teletype device, ":tt", read-only to obtain a descritpor for
> +   * standard input and write-only to obtain a descriptor for standard
> +   * output. Finally, open ":tt" in append mode to obtain a descriptor
> +   * for standard error. Since this is a write mode, most kernels will
> +   * probably return the same value as for standard output, but the
> +   * kernel can differentiate the two using the mode flag and return a
> +   * different descriptor for standard error.
> +   */
> +
>  #ifdef ARM_RDI_MONITOR
>    int volatile block[3];
>    
> @@ -144,7 +154,12 @@
>    block[0] = (int) ":tt";
>    block[2] = 3;     /* length of filename */
>    block[1] = 4;     /* mode "w" */
> -  monitor_stdout = monitor_stderr = do_AngelSWI
> (AngelSWI_Reason_Open, (void *) block);
> +  monitor_stdout = do_AngelSWI (AngelSWI_Reason_Open, (void *) block);
> +
> +  block[0] = (int) ":tt";
> +  block[2] = 3;     /* length of filename */
> +  block[1] = 8;     /* mode "a" */
> +  monitor_stderr = do_AngelSWI (AngelSWI_Reason_Open, (void *) block);
>  #else
>    int fh;
>    const char * name;
> @@ -161,7 +176,14 @@
>         : "=r"(fh)
>         : "i" (SWI_Open),"r"(name)
>         : "r0","r1");
> -  monitor_stdout = monitor_stderr = fh;
> +  monitor_stdout = fh;
> +
> +  name = ":tt";
> +  asm ("mov r0,%2; mov r1, #8; swi %a1; mov %0, r0"
> +       : "=r"(fh)
> +       : "i" (SWI_Open),"r"(name)
> +       : "r0","r1");
> +  monitor_stderr = fh;
>  #endif
>  
>    for (i = 0; i < MAX_OPEN_FILES; i ++)
> @@ -171,6 +193,8 @@
>    openfiles[0].pos = 0;
>    openfiles[1].handle = monitor_stdout;
>    openfiles[1].pos = 0;
> +  openfiles[2].handle = monitor_stderr;
> +  openfiles[2].pos = 0;
>  }
>  
>  static int
>
>
> ------------------------------------------------------------------------
>
> 2005-08-04  Shaun Jackman  <sjackman@gmail.com>
>
> 	* libgloss/syscalls.c (initialise_monitor_handles): Set
> 	monitor_stderr to the result of SWI_open(":tt", "a")
> 	instead of simply duplicating stdout.
>
> Index: libgloss/arm/syscalls.c
> ===================================================================
> RCS file: /cvs/src/src/libgloss/arm/syscalls.c,v
> retrieving revision 1.6
> diff -u -r1.6 syscalls.c
> --- libgloss/arm/syscalls.c	2 Aug 2005 19:17:21 -0000	1.6
> +++ libgloss/arm/syscalls.c	15 Aug 2005 23:05:07 -0000
> @@ -133,6 +133,16 @@
>  {
>    int i;
>    
> +  /* Open the standard file descriptors by opening the special
> +   * teletype device, ":tt", read-only to obtain a descritpor for
> +   * standard input and write-only to obtain a descriptor for standard
> +   * output. Finally, open ":tt" in append mode to obtain a descriptor
> +   * for standard error. Since this is a write mode, most kernels will
> +   * probably return the same value as for standard output, but the
> +   * kernel can differentiate the two using the mode flag and return a
> +   * different descriptor for standard error.
> +   */
> +
>  #ifdef ARM_RDI_MONITOR
>    int volatile block[3];
>    
> @@ -144,7 +154,12 @@
>    block[0] = (int) ":tt";
>    block[2] = 3;     /* length of filename */
>    block[1] = 4;     /* mode "w" */
> -  monitor_stdout = monitor_stderr = do_AngelSWI (AngelSWI_Reason_Open, (void *) block);
> +  monitor_stdout = do_AngelSWI (AngelSWI_Reason_Open, (void *) block);
> +
> +  block[0] = (int) ":tt";
> +  block[2] = 3;     /* length of filename */
> +  block[1] = 8;     /* mode "a" */
> +  monitor_stderr = do_AngelSWI (AngelSWI_Reason_Open, (void *) block);
>  #else
>    int fh;
>    const char * name;
> @@ -161,7 +176,14 @@
>         : "=r"(fh)
>         : "i" (SWI_Open),"r"(name)
>         : "r0","r1");
> -  monitor_stdout = monitor_stderr = fh;
> +  monitor_stdout = fh;
> +
> +  name = ":tt";
> +  asm ("mov r0,%2; mov r1, #8; swi %a1; mov %0, r0"
> +       : "=r"(fh)
> +       : "i" (SWI_Open),"r"(name)
> +       : "r0","r1");
> +  monitor_stderr = fh;
>  #endif
>  
>    for (i = 0; i < MAX_OPEN_FILES; i ++)
> @@ -171,6 +193,8 @@
>    openfiles[0].pos = 0;
>    openfiles[1].handle = monitor_stdout;
>    openfiles[1].pos = 0;
> +  openfiles[2].handle = monitor_stderr;
> +  openfiles[2].pos = 0;
>  }
>  
>  static int