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From: Gerd Hoffmann <kraxel@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Marc-André Lureau" <marcandre.lureau@redhat.com>,
	"Dennis Wölfing" <denniswoelfing@gmx.de>,
	"Gerd Hoffmann" <kraxel@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>
Subject: [PULL 1/3] vga: Allow writing VBE_DISPI_ID5 to ID register
Date: Tue, 15 Jun 2021 19:40:23 +0200	[thread overview]
Message-ID: <20210615174025.3409518-2-kraxel@redhat.com> (raw)
In-Reply-To: <20210615174025.3409518-1-kraxel@redhat.com>

From: Dennis Wölfing <denniswoelfing@gmx.de>

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>
---
 hw/display/vga.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/display/vga.c b/hw/display/vga.c
index 28a90e30d0cf..9d1f66af402e 100644
--- a/hw/display/vga.c
+++ b/hw/display/vga.c
@@ -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;
-- 
2.31.1



  reply	other threads:[~2021-06-15 17:42 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-15 17:40 [PULL 0/3] Vga 20210615 patches Gerd Hoffmann
2021-06-15 17:40 ` Gerd Hoffmann [this message]
2021-06-15 17:40 ` [PULL 2/3] vhost-user-gpu: reorder free calls Gerd Hoffmann
2021-06-15 17:40 ` [PULL 3/3] virtio-gpu: move scanout_id sanity check Gerd Hoffmann
2021-06-16 16:01 ` [PULL 0/3] Vga 20210615 patches Peter Maydell

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