Messages in this thread Patch in this message | | | Date | Wed, 5 Apr 2006 14:17:57 -0700 | From | "Luck, Tony" <> | Subject | Re: 2.6.17-rc1-mm1 |
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On Wed, Apr 05, 2006 at 10:15:34AM -0600, Bjorn Helgaas wrote: > Huh. Intel firmware used to just not mention the VGA framebuffer > (0xa0000-0xc0000) at all in the EFI memory map. I think that was > clearly a bug. So maybe they fixed that by marking it WB (and > hopefully UC as well).
Nope ... not fixed (at least not in the f/w that I'm running). The VGA buffer is still simply not mentioned in the EFI memory map.
The problem looks to come from this code in vgacon.c:
vga_vram_base = VGA_MAP_MEM(vga_vram_base); vga_vram_end = VGA_MAP_MEM(vga_vram_end); vga_vram_size = vga_vram_end - vga_vram_base;
vga_vram_base is 0xb8000, and this call gets a UC return of c0000000000b8000. But vga_vram_end is 0xc0000 ... which is the address of the start of a block of memory that is both WB and UC capable. So ioremap() gives us e0000000000c0000 (which means that vga_vram_size is 2000000000008000, surely the biggest, baddest video card in the history of the world!).
Perhaps the right fix is to subtract 1 from vga_vram_end and pass that into VGA_MAP_MEM(), and then add the 1 byte back when computing the size? But I don't know whether that might do something bad on some other architecture that uses vgacon.c. If this is not acceptable, then we can fall back and use the Nanhai/Bjorn fix of using ioremap_nocache().
Signed-off-by: Tony Luck <tony.luck@intel.com>
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diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c index d5a04b6..4ca9877 100644 --- a/drivers/video/console/vgacon.c +++ b/drivers/video/console/vgacon.c @@ -484,8 +484,8 @@ #endif } vga_vram_base = VGA_MAP_MEM(vga_vram_base); - vga_vram_end = VGA_MAP_MEM(vga_vram_end); - vga_vram_size = vga_vram_end - vga_vram_base; + vga_vram_end = VGA_MAP_MEM(vga_vram_end - 1); + vga_vram_size = vga_vram_end - vga_vram_base + 1; /* * Find out if there is a graphics card present. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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