This version reuses an "old" scrollback buffer of the previous console if memory allocation fails.
However, the issue of clearing the console using the 'clear_console' commnad [1,2] is still unsolved. I'd prefer implementing it using a ioctl() call but it's open for discussion ;) [1] https://sources.debian.net/src/bash/4.2% 2Bdfsg-0.1/debian/clear_console.c [2] http://manpages.debian.org/cgi-bin/man.cgi?query=clear_console On So, 2014-06-15 at 01:15 +0200, Manuel Schölling wrote: > Add a scrollback buffers for each VGA console. The benefit is that > the scrollback history is not flushed when switching between consoles > but is persistent. > The buffers are allocated on demand when a new console is opened. > > Signed-off-by: Manuel Schölling <manuel.schoell...@gmx.de> > --- > drivers/video/console/Kconfig | 19 ++++- > drivers/video/console/vgacon.c | 159 > +++++++++++++++++++++++++++------------- > 2 files changed, 124 insertions(+), 54 deletions(-) > > diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig > index fe1cd01..05fdc2c 100644 > --- a/drivers/video/console/Kconfig > +++ b/drivers/video/console/Kconfig > @@ -43,9 +43,22 @@ config VGACON_SOFT_SCROLLBACK_SIZE > range 1 1024 > default "64" > help > - Enter the amount of System RAM to allocate for the scrollback > - buffer. Each 64KB will give you approximately 16 80x25 > - screenfuls of scrollback buffer > + Enter the amount of System RAM to allocate for scrollback > + buffers of VGA consoles. Each 64KB will give you approximately > + 16 80x25 screenfuls of scrollback buffer. > + > +config VGACON_SOFT_SCROLLBACK_FOR_EACH_CONSOLE > + bool "Persistent Scrollback History for each console" > + depends on VGACON_SOFT_SCROLLBACK > + default y > + help > + Say Y here if for each VGA console a scrollback buffer should > + be allocated. The scrollback history will persist when switching > + between consoles. If you say N here, scrollback is only supported > + for the active VGA console and scrollback history will be flushed > + when switching between consoles. > + > + If you use a RAM-constrained system, say N here. > > config MDA_CONSOLE > depends on !M68K && !PARISC && ISA > diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c > index 9d8feac..652131d 100644 > --- a/drivers/video/console/vgacon.c > +++ b/drivers/video/console/vgacon.c > @@ -181,70 +181,126 @@ static inline void vga_set_mem_top(struct vc_data *c) > > #ifdef CONFIG_VGACON_SOFT_SCROLLBACK > /* software scrollback */ > -static void *vgacon_scrollback; > -static int vgacon_scrollback_tail; > -static int vgacon_scrollback_size; > -static int vgacon_scrollback_rows; > -static int vgacon_scrollback_cnt; > -static int vgacon_scrollback_cur; > -static int vgacon_scrollback_save; > -static int vgacon_scrollback_restore; > - > -static void vgacon_scrollback_init(int pitch) > +struct vgacon_scrollback_info { > + void *data; > + int tail; > + int size; > + int rows; > + int cnt; > + int cur; > + int save; > + int restore; > +}; > +static struct vgacon_scrollback_info *vgacon_scrollback_cur; > +#ifdef CONFIG_VGACON_SOFT_SCROLLBACK_FOR_EACH_CONSOLE > +static struct vgacon_scrollback_info vgacon_scrollbacks[MAX_NR_CONSOLES]; > +#else > +static struct vgacon_scrollback_info vgacon_scrollbacks[1]; > +#endif > + > +static void vgacon_scrollback_reset(size_t reset_size) > { > - int rows = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024/pitch; > - > - if (vgacon_scrollback) { > - vgacon_scrollback_cnt = 0; > - vgacon_scrollback_tail = 0; > - vgacon_scrollback_cur = 0; > - vgacon_scrollback_rows = rows - 1; > - vgacon_scrollback_size = rows * pitch; > + if (vgacon_scrollback_cur->data && reset_size > 0) > + memset(vgacon_scrollback_cur->data, 0, reset_size); > + > + vgacon_scrollback_cur->cnt = 0; > + vgacon_scrollback_cur->tail = 0; > + vgacon_scrollback_cur->cur = 0; > +} > + > +static void vgacon_scrollback_init(int vc_num) > +{ > + int pitch = vga_video_num_columns * 2; > + size_t size = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024; > + int rows = size/pitch; > + void *data; > + > + data = kcalloc(CONFIG_VGACON_SOFT_SCROLLBACK_SIZE, 1024, GFP_NOWAIT); > + if (data) { > + vgacon_scrollbacks[vc_num].data = data; > + vgacon_scrollback_cur = &vgacon_scrollbacks[vc_num]; > + > + vgacon_scrollback_cur->rows = rows - 1; > + vgacon_scrollback_cur->size = rows * pitch; > + > + vgacon_scrollback_reset(0); > + } else { > + pr_warn("VGAcon: failed to allocate memory for scrollback. > Trying to reuse previous buffer.\n"); > + /* leave vgacon_scrollback_cur untouched > + but reset its content */ > + vgacon_scrollback_reset(size); > } > } > > +static void vgacon_switch_scrollback(int vc_num) > +{ > +#ifdef CONFIG_VGACON_SOFT_SCROLLBACK_FOR_EACH_CONSOLE > + if (!vgacon_scrollbacks[vc_num].data) > + vgacon_scrollback_init(vc_num); > + else > + vgacon_scrollback_cur = &vgacon_scrollbacks[vc_num]; > +#else > + vc_num = 0; > + > + if (!vgacon_scrollbacks[vc_num].data) > + vgacon_scrollback_init(vc_num); > + else { > + size_t size = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024; > + > + vgacon_scrollback_reset(size); > + } > +#endif > +} > + > static void vgacon_scrollback_startup(void) > { > - vgacon_scrollback = kcalloc(CONFIG_VGACON_SOFT_SCROLLBACK_SIZE, 1024, > GFP_NOWAIT); > - vgacon_scrollback_init(vga_video_num_columns * 2); > + int i; > + > + for (i = 0; i < ARRAY_SIZE(vgacon_scrollbacks); ++i) > + vgacon_scrollbacks[i].data = NULL; > + > + vgacon_scrollback_cur = &vgacon_scrollbacks[0]; > + vgacon_scrollback_init(0); > } > > static void vgacon_scrollback_update(struct vc_data *c, int t, int count) > { > void *p; > > - if (!vgacon_scrollback_size || c->vc_num != fg_console) > + if (!vgacon_scrollback_cur->data || !vgacon_scrollback_cur->size) > return; > > p = (void *) (c->vc_origin + t * c->vc_size_row); > > while (count--) { > - scr_memcpyw(vgacon_scrollback + vgacon_scrollback_tail, > + scr_memcpyw(vgacon_scrollback_cur->data + > + vgacon_scrollback_cur->tail, > p, c->vc_size_row); > - vgacon_scrollback_cnt++; > + > + vgacon_scrollback_cur->cnt++; > p += c->vc_size_row; > - vgacon_scrollback_tail += c->vc_size_row; > + vgacon_scrollback_cur->tail += c->vc_size_row; > > - if (vgacon_scrollback_tail >= vgacon_scrollback_size) > - vgacon_scrollback_tail = 0; > + if (vgacon_scrollback_cur->tail >= vgacon_scrollback_cur->size) > + vgacon_scrollback_cur->tail = 0; > > - if (vgacon_scrollback_cnt > vgacon_scrollback_rows) > - vgacon_scrollback_cnt = vgacon_scrollback_rows; > + if (vgacon_scrollback_cur->cnt > vgacon_scrollback_cur->rows) > + vgacon_scrollback_cur->cnt = > vgacon_scrollback_cur->rows; > > - vgacon_scrollback_cur = vgacon_scrollback_cnt; > + vgacon_scrollback_cur->cur = vgacon_scrollback_cur->cnt; > } > } > > static void vgacon_restore_screen(struct vc_data *c) > { > - vgacon_scrollback_save = 0; > + vgacon_scrollback_cur->save = 0; > > - if (!vga_is_gfx && !vgacon_scrollback_restore) { > + if (!vga_is_gfx && !vgacon_scrollback_cur->restore) { > scr_memcpyw((u16 *) c->vc_origin, (u16 *) c->vc_screenbuf, > c->vc_screenbuf_size > vga_vram_size ? > vga_vram_size : c->vc_screenbuf_size); > - vgacon_scrollback_restore = 1; > - vgacon_scrollback_cur = vgacon_scrollback_cnt; > + vgacon_scrollback_cur->restore = 1; > + vgacon_scrollback_cur->cur = vgacon_scrollback_cur->cnt; > } > } > > @@ -258,41 +314,41 @@ static int vgacon_scrolldelta(struct vc_data *c, int > lines) > return 1; > } > > - if (!vgacon_scrollback) > + if (!vgacon_scrollback_cur->data) > return 1; > > - if (!vgacon_scrollback_save) { > + if (!vgacon_scrollback_cur->save) { > vgacon_cursor(c, CM_ERASE); > vgacon_save_screen(c); > - vgacon_scrollback_save = 1; > + vgacon_scrollback_cur->save = 1; > } > > - vgacon_scrollback_restore = 0; > - start = vgacon_scrollback_cur + lines; > + vgacon_scrollback_cur->restore = 0; > + start = vgacon_scrollback_cur->cur + lines; > end = start + abs(lines); > > if (start < 0) > start = 0; > > - if (start > vgacon_scrollback_cnt) > - start = vgacon_scrollback_cnt; > + if (start > vgacon_scrollback_cur->cnt) > + start = vgacon_scrollback_cur->cnt; > > if (end < 0) > end = 0; > > - if (end > vgacon_scrollback_cnt) > - end = vgacon_scrollback_cnt; > + if (end > vgacon_scrollback_cur->cnt) > + end = vgacon_scrollback_cur->cnt; > > - vgacon_scrollback_cur = start; > + vgacon_scrollback_cur->cur = start; > count = end - start; > - soff = vgacon_scrollback_tail - ((vgacon_scrollback_cnt - end) * > - c->vc_size_row); > + soff = vgacon_scrollback_cur->tail - > + ((vgacon_scrollback_cur->cnt - end) * c->vc_size_row); > soff -= count * c->vc_size_row; > > if (soff < 0) > - soff += vgacon_scrollback_size; > + soff += vgacon_scrollback_cur->size; > > - count = vgacon_scrollback_cnt - start; > + count = vgacon_scrollback_cur->cnt - start; > > if (count > c->vc_rows) > count = c->vc_rows; > @@ -306,13 +362,13 @@ static int vgacon_scrolldelta(struct vc_data *c, int > lines) > > count *= c->vc_size_row; > /* how much memory to end of buffer left? */ > - copysize = min(count, vgacon_scrollback_size - soff); > - scr_memcpyw(d, vgacon_scrollback + soff, copysize); > + copysize = min(count, vgacon_scrollback_cur->size - soff); > + scr_memcpyw(d, vgacon_scrollback_cur->data + soff, copysize); > d += copysize; > count -= copysize; > > if (count) { > - scr_memcpyw(d, vgacon_scrollback, count); > + scr_memcpyw(d, vgacon_scrollback_cur->data, count); > d += count; > } > > @@ -327,6 +383,7 @@ static int vgacon_scrolldelta(struct vc_data *c, int > lines) > #define vgacon_scrollback_startup(...) do { } while (0) > #define vgacon_scrollback_init(...) do { } while (0) > #define vgacon_scrollback_update(...) do { } while (0) > +#define vgacon_switch_scrollback(...) do { } while (0) > > static void vgacon_restore_screen(struct vc_data *c) > { > @@ -842,7 +899,7 @@ static int vgacon_switch(struct vc_data *c) > vgacon_doresize(c, c->vc_cols, c->vc_rows); > } > > - vgacon_scrollback_init(c->vc_size_row); > + vgacon_switch_scrollback(c->vc_num); > return 0; /* Redrawing not needed */ > } > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
