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vga: Allow writing VBE_DISPI_ID5 to ID register 

The highest VBE_DISPI_INDEX_ID version supported by QEMU is
VBE_DISPI_ID5. But currently QEMU only allows writing values up to
VBE_DISPI_ID4 to the VBE_DISPI_INDEX_ID register.

As a result of this when a lower version is written to this register and
later VBE_DISPI_ID5 is written back, reads from the register will
continue to report the lower version.

Indeed SeaBIOS is doing that during VGA initialization which causes
guests to always read VBE_DISPI_ID0 instead of the correct version.

Signed-off-by: Dennis Wölfing <denniswoelfing@gmx.de>
Message-Id: <20210607115303.228659-1-denniswoelfing@gmx.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Dennis Wölfing 2021-06-07 13:53:03 +02:00 committed by Gerd Hoffmann
parent 1ea06abcee
commit 05ece98f96
1 changed files with 2 additions and 1 deletions
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3
hw/display/vga.c
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@ -752,7 +752,8 @@ void vbe_ioport_write_data(void *opaque, uint32_t addr, uint32_t val)
val == VBE_DISPI_ID1 ||
val == VBE_DISPI_ID2 ||
val == VBE_DISPI_ID3 ||
val == VBE_DISPI_ID4) {
val == VBE_DISPI_ID4 ||
val == VBE_DISPI_ID5) {
s->vbe_regs[s->vbe_index] = val;
}
break;