Re: [Minios-devel] [UNIKRAFT PATCH v2 1/1] plat/kvm: Update VGA console cursor location

[Florian Schmidt <Florian.Schmidt@xxxxxxxxx>]

On 08/22/2018 03:51 PM, Florian Schmidt wrote:
> Update the location of the cursor as data is written to the console.
> Note that this does not set the cursor location registers, hence all we
> get is the blinking underline character, not the full-size block
> character.
... aaand I forgot to update the commit message. Just ignore the second 
sentence, it should only be the first one.
Sorry,
Florian

> Signed-off-by: Florian Schmidt <florian.schmidt@xxxxxxxxx>
> ---
>   plat/kvm/x86/vga_console.c | 47 ++++++++++++++++++++++++++++++++++++++
>   1 file changed, 47 insertions(+)
>
> diff --git a/plat/kvm/x86/vga_console.c b/plat/kvm/x86/vga_console.c
> index ff825e3..f565b1c 100644
> --- a/plat/kvm/x86/vga_console.c
> +++ b/plat/kvm/x86/vga_console.c
> @@ -29,6 +29,8 @@
>   #include <sys/types.h>
>   #include <stdint.h>
>   #include <string.h>
> +#include <x86/cpu.h>
> +#include <x86/irq.h>
>   #include <kvm-x86/vga_console.h>
>   
>   /* Hardware text mode color constants. */
> @@ -69,6 +71,8 @@ static size_t terminal_row;
>   static size_t terminal_column;
>   static uint8_t terminal_color;
>   static uint16_t *terminal_buffer;
> +static uint16_t areg;   /* VGA address register */
> +static uint16_t dreg;   /* VGA data register */
>   
>   static void clear_terminal(void)
>   {
> @@ -83,9 +87,36 @@ static void clear_terminal(void)
>   
>   void _libkvmplat_init_vga_console(void)
>   {
> +       unsigned long irq_flags;
> +
>         terminal_row = 0;
>         terminal_column = 0;
>         terminal_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
> +
> +       local_irq_save(irq_flags);
> +       /* Location of the address and data registers is variable and denoted
> +        * by the least significant bit in the Input/Output register located
> +        * at 0x3cc. For our emulated color display, they should always be
> +        * 0x3d{4,5}, but better safe than sorry, so let's check at init time.
> +        */
> +       if (inb(0x3cc) & 0x1) {
> +               areg = 0x3d4;
> +               dreg = 0x3d5;
> +       } else {
> +               areg = 0x3b4;
> +               dreg = 0x3b5;
> +       }
> +
> +       /* Initialize cursor appearance. Setting CURSOR_START (0x0a) to 0x0e
> +        * and CURSOR_END (0x0b) to 0x0f enables the cursor and produces
> +        * a blinking underscore.
> +        */
> +       outb(areg, 0x0a);
> +       outb(dreg, 0x0e);
> +       outb(areg, 0x0b);
> +       outb(dreg, 0x0f);
> +       local_irq_restore(irq_flags);
> +
>         terminal_buffer = (uint16_t *) 0xb8000;
>         clear_terminal();
>   }
> @@ -109,6 +140,21 @@ static void vga_scroll(void)
>                         = vga_entry(' ', terminal_color);
>   }
>   
> +static void vga_update_cursor(void)
> +{
> +       unsigned long irq_flags;
> +       uint8_t old;
> +
> +       local_irq_save(irq_flags);
> +       old = inb(areg);
> +       outb(areg, 0x0e); // Cursor Location High
> +       outb(dreg, ((terminal_row * VGA_WIDTH) + terminal_column) >> 8);
> +       outb(areg, 0x0f); // Cursor Location Low
> +       outb(dreg, ((terminal_row * VGA_WIDTH) + terminal_column) & 0xff);
> +       outb(areg, old);
> +       local_irq_restore(irq_flags);
> +}
> +
>   static void vga_newline(void)
>   {
>         if (terminal_row == VGA_HEIGHT - 1)
> @@ -157,4 +203,5 @@ void _libkvmplat_vga_putc(char c)
>                 }
>                 break;
>         }
> +       vga_update_cursor();
>   }
--
Dr. Florian Schmidt
フローリアン・シュミット
Research Scientist,
Systems and Machine Learning Group
NEC Laboratories Europe
Kurfürsten-Anlage 36, D-69115 Heidelberg
Tel.     +49 (0)6221 4342-265
Fax:     +49 (0)6221 4342-155
e-mail:  florian.schmidt@xxxxxxxxx
============================================================
Registered at Amtsgericht Mannheim, Germany, HRB728558

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