Since the VBE mode attributes indicate that all modes are not VGA compatible, applications must use VBE function 09h to manipulate the palette rather than directly accessing the VGA registers.
This implementation uses the standard VGA registers for all hardware, which may not be appropriate; I only verified qemu -device VGA.
Without this patch, the get/set palette function returns an error code, so programs that use 8-bit indexed color modes fail. For example, Quake (DOS) printed "Error: Unable to load VESA palette" and exited when trying to set a SVGA mode like 640x480, but with the patch it succeeds. This fixes qemu issue #251 and #1862.
https://gitlab.com/qemu-project/qemu/-/issues/251 https://gitlab.com/qemu-project/qemu/-/issues/1862
Signed-off-by: Daniel Verkamp daniel@drv.nu --- src/std/vbe.h | 7 +++++++ vgasrc/stdvga.h | 3 +++ vgasrc/stdvgaio.c | 30 ++++++++++++++++++++++++++++++ vgasrc/vbe.c | 42 ++++++++++++++++++++++++++++++++++++++++++ vgasrc/vgahw.h | 8 ++++++++ 5 files changed, 90 insertions(+)
diff --git a/src/std/vbe.h b/src/std/vbe.h index fe96f5ec..fddaa4fd 100644 --- a/src/std/vbe.h +++ b/src/std/vbe.h @@ -88,6 +88,13 @@ struct vbe_crtc_info { u8 reserved[40]; } PACKED;
+struct vbe_palette_entry { + u8 blue; + u8 green; + u8 red; + u8 align; +} PACKED; + /* VBE Return Status Info */ /* AL */ #define VBE_RETURN_STATUS_SUPPORTED 0x4F diff --git a/vgasrc/stdvga.h b/vgasrc/stdvga.h index 4184c600..af10fd78 100644 --- a/vgasrc/stdvga.h +++ b/vgasrc/stdvga.h @@ -74,6 +74,9 @@ int stdvga_get_displaystart(struct vgamode_s *vmode_g); int stdvga_set_displaystart(struct vgamode_s *vmode_g, int val); int stdvga_get_dacformat(struct vgamode_s *vmode_g); int stdvga_set_dacformat(struct vgamode_s *vmode_g, int val); +struct vbe_palette_entry; +int stdvga_set_palette_colors(u16 seg, struct vbe_palette_entry *pal_far, u8 start, int count); +int stdvga_get_palette_colors(u16 seg, struct vbe_palette_entry *pal_far, u8 start, int count); int stdvga_save_restore(int cmd, u16 seg, void *data); void stdvga_enable_video_addressing(u8 disable); int stdvga_setup(void); diff --git a/vgasrc/stdvgaio.c b/vgasrc/stdvgaio.c index 77fcecdf..ec22c4a1 100644 --- a/vgasrc/stdvgaio.c +++ b/vgasrc/stdvgaio.c @@ -6,6 +6,7 @@
#include "farptr.h" // GET_FARVAR #include "stdvga.h" // VGAREG_PEL_MASK +#include "std/vbe.h" // vbe_palette_entry #include "vgautil.h" // stdvga_pelmask_read #include "x86.h" // inb
@@ -184,3 +185,32 @@ stdvga_dac_write(u16 seg, u8 *data_far, u8 start, int count) count--; } } + +int +stdvga_set_palette_colors(u16 seg, struct vbe_palette_entry *pal_far, u8 start, int count) +{ + outb(start, VGAREG_DAC_WRITE_ADDRESS); + while (count) { + outb(GET_FARVAR(seg, pal_far->red), VGAREG_DAC_DATA); + outb(GET_FARVAR(seg, pal_far->green), VGAREG_DAC_DATA); + outb(GET_FARVAR(seg, pal_far->blue), VGAREG_DAC_DATA); + pal_far++; + count--; + } + return 0; +} + +int +stdvga_get_palette_colors(u16 seg, struct vbe_palette_entry *pal_far, u8 start, int count) +{ + outb(start, VGAREG_DAC_READ_ADDRESS); + while (count) { + SET_FARVAR(seg, pal_far->red, inb(VGAREG_DAC_DATA)); + SET_FARVAR(seg, pal_far->green, inb(VGAREG_DAC_DATA)); + SET_FARVAR(seg, pal_far->blue, inb(VGAREG_DAC_DATA)); + SET_FARVAR(seg, pal_far->align, 0); + pal_far++; + count--; + } + return 0; +} diff --git a/vgasrc/vbe.c b/vgasrc/vbe.c index 91abc9ab..0ac88805 100644 --- a/vgasrc/vbe.c +++ b/vgasrc/vbe.c @@ -376,6 +376,47 @@ fail: regs->ax = 0x014f; }
+static void +vbe_104f09(struct bregs *regs) +{ + struct vgamode_s *vmode_g = get_current_mode(); + if (! vmode_g) + goto fail; + u8 memmodel = GET_GLOBAL(vmode_g->memmodel); + u8 depth = GET_GLOBAL(vmode_g->depth); + if (memmodel == MM_DIRECT || memmodel == MM_YUV || depth > 8) { + regs->ax = 0x034f; + return; + } + if (regs->dh) + goto fail; + u8 start = regs->dl; + int count = regs->cx; + int max_colors = 1 << depth; + if (start + count > max_colors) + goto fail; + u16 seg = regs->es; + struct vbe_palette_entry *pal = (void*)(regs->di+0); + int ret; + switch (regs->bl) { + case 0x80: + case 0x00: + ret = vgahw_set_palette_colors(seg, pal, start, count); + break; + case 0x01: + ret = vgahw_get_palette_colors(seg, pal, start, count); + break; + default: + goto fail; + } + if (ret < 0) + goto fail; + regs->ax = 0x004f; + return; +fail: + regs->ax = 0x014f; +} + static void vbe_104f0a(struct bregs *regs) { @@ -456,6 +497,7 @@ handle_104f(struct bregs *regs) case 0x06: vbe_104f06(regs); break; case 0x07: vbe_104f07(regs); break; case 0x08: vbe_104f08(regs); break; + case 0x09: vbe_104f09(regs); break; case 0x0a: vbe_104f0a(regs); break; case 0x10: vbe_104f10(regs); break; case 0x15: vbe_104f15(regs); break; diff --git a/vgasrc/vgahw.h b/vgasrc/vgahw.h index 8b64660e..684530d6 100644 --- a/vgasrc/vgahw.h +++ b/vgasrc/vgahw.h @@ -141,6 +141,14 @@ static inline int vgahw_set_dacformat(struct vgamode_s *vmode_g, int val) { return stdvga_set_dacformat(vmode_g, val); }
+static inline int vgahw_set_palette_colors(u16 seg, struct vbe_palette_entry *pal_far, u8 start, int count) { + return stdvga_set_palette_colors(seg, pal_far, start, count); +} + +static inline int vgahw_get_palette_colors(u16 seg, struct vbe_palette_entry *pal_far, u8 start, int count) { + return stdvga_get_palette_colors(seg, pal_far, start, count); +} + static inline int vgahw_save_restore(int cmd, u16 seg, void *data) { if (CONFIG_VGA_CIRRUS) return clext_save_restore(cmd, seg, data);