x86, setup: Don't skip mode setting for the standard VGA modes
The code for setting standard VGA modes probes for the current mode, and skips the mode setting if the mode is 3 (color text 80x25) or 7 (mono text 80x25). Unfortunately, there are BIOSes, including the VMware BIOS, which report the previous mode if function 0F is queried while the screen is in a VESA mode, and of course, nothing can help a mode poked directly into the hardware. As such, the safe option is to set the mode anyway, and only query to see if we should be using mode 7 rather than mode 3. People who don't want any mode setting at all should probably use vga=0x0f04 (VIDEO_CURRENT_MODE). It's possible that should be the kernel default. Reported-by Rene Arends <R.R.Arends@hro.nl> Signed-off-by: H. Peter Anvin <hpa@zytor.com> LKML-Reference: <tip-*@git.kernel.org>
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@ -42,22 +42,15 @@ static u8 vga_set_basic_mode(void)
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{
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struct biosregs ireg, oreg;
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u16 ax;
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u8 rows;
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u8 mode;
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initregs(&ireg);
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/* Query current mode */
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ax = 0x0f00;
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intcall(0x10, &ireg, &oreg);
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mode = oreg.al;
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set_fs(0);
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rows = rdfs8(0x484); /* rows minus one */
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if ((oreg.ax == 0x5003 || oreg.ax == 0x5007) &&
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(rows == 0 || rows == 24))
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return mode;
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if (mode != 3 && mode != 7)
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mode = 3;
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