The patch titled
Detaching fbcon: fix vgacon to allow retaking of the console
has been added to the -mm tree. Its filename is
detaching-fbcon-fix-vgacon-to-allow-retaking-of-the.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Detaching fbcon: fix vgacon to allow retaking of the console
From: "Antonino A. Daplas" <adaplas@xxxxxxxxx>
One of the limitations of the framebuffer console system is its inablity to
unload or detach itself from the console layer. And once it loads, it also
locks in framebuffer drivers preventing their unload. Although the con2fbmap
utility does provide a means to unload individual drivers, it requires that at
least one framebuffer driver is loaded for use by fbcon.
With this change, it is possible to detach fbcon from the console layer. If it
is detached, it will reattach the boot console driver (which is permanently
loaded) back to the console layer so the system can continue to work. As a
consequence, fbcon will also decrement its reference count of individual
framebuffer drivers, allowing all of these drivers to be unloaded even if
fbcon is still loaded.
Unless you use drivers that restores the display to text mode (rivafb and
i810fb, for example), detaching fbcon does require assistance from userspace
tools (ie, vbetools) for text mode to be restored completely. Without the
help of these tools, fbcon will leave the VGA console corrupted. The methods
that can be used will be described in Documentation/fb/fbcon.txt.
Because the vt layer also increments the module reference count for each
console driver, fbcon cannot be directly unloaded. It must be detached first
prior to unload.
Similarly, fbcon can be reattached to the console layer without having to
reload the module. A nice feature if fbcon is compiled statically.
Attaching and detaching fbcon is done via sysfs attributes. A class device
entry for fbcon is created in /sys/class/graphics. The two attributes that
controls this feature are detach and attach. Two other attributes that are
piggybacked under /sys/class/graphics/fb[n] that are fbcon-specific,
'con_rotate' and 'con_rotate_all' are moved to fbcon. They are renamed as
'rotate' and 'rotate_all' respectively.
Overall, this feature is a great help for developers working in the
framebuffer or console layer. There is not need to continually reboot the
kernel for every small change. It is also useful for regular users who wants
to choose between a graphical console or a text console without having to
reboot.
Example usage for x86:
/* start in text mode */
modprobe xxxfb
modprobe fbcon
/* graphical mode with fbcon using xxxfb */
echo 1 > /sys/class/graphics/fbcon/detach
/* back to text mode, will produce corrupt display unless vbetool is used */
rmmod xxxfb
modprobe yyyfb
/* back to graphical mode with fbcon using yyyfb */
Before trying out this feature, please read Documentation/fb/fbcon.txt.
This patch:
In order for fbcon to detach itself from the console layer, vgacon, which is a
boot console driver, must be fixed so it can retake the console multiple
times, not just during init. The following needs to be done:
- remove __init from the vgacon_startup, this is called again by
take_over_console().
- vc->rows and vc->cols are set manually by vgacon during init. After init,
vc_resize() can be used
- make sure the scrollback_buffer is not reallocated
Signed-off-by: Antonino Daplas <adaplas@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/video/console/vgacon.c | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)
diff -puN drivers/video/console/vgacon.c~detaching-fbcon-fix-vgacon-to-allow-retaking-of-the drivers/video/console/vgacon.c
--- devel/drivers/video/console/vgacon.c~detaching-fbcon-fix-vgacon-to-allow-retaking-of-the 2006-06-06 15:12:48.000000000 -0700
+++ devel-akpm/drivers/video/console/vgacon.c 2006-06-06 15:12:48.000000000 -0700
@@ -114,6 +114,7 @@ static int vga_512_chars;
static int vga_video_font_height;
static int vga_scan_lines;
static unsigned int vga_rolled_over = 0;
+static int vga_init_done;
static int __init no_scroll(char *str)
{
@@ -190,7 +191,7 @@ static void vgacon_scrollback_init(int p
}
}
-static void __init vgacon_scrollback_startup(void)
+static void vgacon_scrollback_startup(void)
{
vgacon_scrollback = alloc_bootmem(CONFIG_VGACON_SOFT_SCROLLBACK_SIZE
* 1024);
@@ -355,7 +356,7 @@ static int vgacon_scrolldelta(struct vc_
}
#endif /* CONFIG_VGACON_SOFT_SCROLLBACK */
-static const char __init *vgacon_startup(void)
+static const char *vgacon_startup(void)
{
const char *display_desc = NULL;
u16 saved1, saved2;
@@ -523,7 +524,12 @@ static const char __init *vgacon_startup
vgacon_xres = ORIG_VIDEO_COLS * VGA_FONTWIDTH;
vgacon_yres = vga_scan_lines;
- vgacon_scrollback_startup();
+
+ if (!vga_init_done) {
+ vgacon_scrollback_startup();
+ vga_init_done = 1;
+ }
+
return display_desc;
}
@@ -531,10 +537,20 @@ static void vgacon_init(struct vc_data *
{
unsigned long p;
- /* We cannot be loaded as a module, therefore init is always 1 */
+ /*
+ * We cannot be loaded as a module, therefore init is always 1,
+ * but vgacon_init can be called more than once, and init will
+ * not be 1.
+ */
c->vc_can_do_color = vga_can_do_color;
- c->vc_cols = vga_video_num_columns;
- c->vc_rows = vga_video_num_lines;
+
+ /* set dimensions manually if init != 0 since vc_resize() will fail */
+ if (init) {
+ c->vc_cols = vga_video_num_columns;
+ c->vc_rows = vga_video_num_lines;
+ } else
+ vc_resize(c, vga_video_num_columns, vga_video_num_lines);
+
c->vc_scan_lines = vga_scan_lines;
c->vc_font.height = vga_video_font_height;
c->vc_complement_mask = 0x7700;
_
Patches currently in -mm which might be from adaplas@xxxxxxxxx are
git-intelfb.patch
savagefb-allocate-space-for-current-and-saved-register.patch
savagefb-add-state-save-and_restore-hooks.patch
savagefb-add-state-save-and_restore-hooks-fix.patch
fbdev-more-accurate-sync-range-extrapolation.patch
nvidiafb-revise-pci_device_id-table.patch
atyfb-fix-hardware-cursor-handling.patch
atyfb-remove-unneeded-calls-to-wait_for_idle.patch
atyfb-set-correct-acceleration-flags.patch
epson1355fb-update-platform-code.patch
vesafb-update-platform-code.patch
vfb-update-platform-code.patch
vga16fb-update-platform-code.patch
fbdev-static-pseudocolor-with-depth-less-than-4-does.patch
savagefb-whitespace-cleanup.patch
fbdev-firmware-edid-fixes.patch
nvidiafb-add-support-for-geforce-6100-and-related-chipsets.patch
vesafb-fix-return-code-of-vesafb_setcolreg.patch
vesafb-prefer-vga-registers-over-pmi.patch
atyfb-fix-dead-code.patch
fbdev-coverity-bug-85.patch
fbdev-coverity-bug-90.patch
backlight-fix-kconfig-dependency.patch
detaching-fbcon-fix-vgacon-to-allow-retaking-of-the.patch
detaching-fbcon-fix-give_up_console.patch
detaching-fbcon-remove-calls-to-pci_disable_device.patch
detaching-fbcon-add-sysfs-class-device-entry-for-fbcon.patch
detaching-fbcon-clean-up-exit-code.patch
detaching-fbcon-add-capability-to-attach-detach-fbcon.patch
detaching-fbcon-update-documentation.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
