[Qemu-devel] [Bug 1777672] Re: QEMU aarch64 virtual/physical frame buffer
Just submitted this patchset to the list which should fix this bug:
https://patchwork.ozlabs.org/project/qemu-devel/list/?series=60775
** Changed in: qemu
Status: New => In Progress
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https://bugs.launchpad.net/bugs/1777672
Title:
QEMU aarch64 virtual/physical frame buffer
Status in QEMU:
In Progress
Bug description:
I fully recognize that the error here could be mine, but the code is
pretty simple and straightforward; When emulating a Raspberry PI 3
using aarch64 and allocating a virtual framebuffer larger than the
physical frambuffer (for double-buffering purposes), the QEMU window
shows the full size of the *virtual* framebuffer rather than the size
of the *physical* framebuffer.
You can replicate this with code such as:
#define FBWIDTH 1024
#define FBHEIGHT 768
void lfb_init()
{
uart_puts("Initializing Framebuffer\n");
mbox[0] = 35*4;
mbox[1] = MBOX_REQUEST;
mbox[2] = 0x48003; //set phy wh
mbox[3] = 8;
mbox[4] = 8;
mbox[5] = FBWIDTH; //FrameBufferInfo.width
mbox[6] = FBHEIGHT; //FrameBufferInfo.height
mbox[7] = 0x48004; //set virt wh
mbox[8] = 8;
mbox[9] = 8;
mbox[10] = FBWIDTH;//FrameBufferInfo.virtual_width
mbox[11] = FBHEIGHT * 2; //FrameBufferInfo.virtual_height
mbox[12] = 0x48009; //set virt offset
mbox[13] = 8;
mbox[14] = 8;
mbox[15] = 0; //FrameBufferInfo.x_offset
mbox[16] = 0; //FrameBufferInfo.y.offset
mbox[17] = 0x48005; //set depth
mbox[18] = 4;
mbox[19] = 4;
mbox[20] = 32; //FrameBufferInfo.depth
mbox[21] = 0x48006; //set pixel order
mbox[22] = 4;
mbox[23] = 4;
mbox[24] = 1; //RGB, not BGR preferably
mbox[25] = 0x40001; //get framebuffer, gets alignment on request
mbox[26] = 8;
mbox[27] = 8;
mbox[28] = 4096;//FrameBufferInfo.pointer
mbox[29] = 0; //FrameBufferInfo.size
mbox[30] = 0x40008; //get pitch
mbox[31] = 4;
mbox[32] = 4;
mbox[33] = 0; //FrameBufferInfo.pitch
mbox[34] = MBOX_TAG_LAST;
if(mbox_call(MBOX_CH_PROP) && mbox[20]==32 && mbox[28]!=0) {
mbox[28]&=0x3FFF;
fbwidth=mbox[5];
fbheight=mbox[6];
pitch=mbox[33];
lfb=(void*)((unsigned long)mbox[28]);
}
}
I will assume, for the sake of this posting, that the reader
understands the mailbox architecture and the appropriate address
definitions for them. The key point is that allocating a virtual
buffer twice the height of the physical buffer results in QEMU
improperly displaying a double-height window.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1777672/+subscriptions
[Qemu-devel] [Bug 1777672] Re: QEMU aarch64 virtual/physical frame buffer
Mmm. I guess the wiki page is just wrong, then. I have some prototype patches
that work, but I need to check somehow what the real hardware's response to
various edge cases is:
* trying to set a virtual screen size that's smaller than the physical screen
size
* trying to set the virtual x/y offsets to values that put the physical
viewport partially outside the virtual screen (eg setting height = vheight =
480, width = vwidth = 640, xoffset = yoffset = 50)
There's a mechanism in the mbox API for saying "can't do that" but I
don't know whether that sort of thing actually does result in failure to
set the height or the offset or whatever...
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https://bugs.launchpad.net/bugs/1777672
Title:
QEMU aarch64 virtual/physical frame buffer
Status in QEMU:
New
Bug description:
I fully recognize that the error here could be mine, but the code is
pretty simple and straightforward; When emulating a Raspberry PI 3
using aarch64 and allocating a virtual framebuffer larger than the
physical frambuffer (for double-buffering purposes), the QEMU window
shows the full size of the *virtual* framebuffer rather than the size
of the *physical* framebuffer.
You can replicate this with code such as:
#define FBWIDTH 1024
#define FBHEIGHT 768
void lfb_init()
{
uart_puts("Initializing Framebuffer\n");
mbox[0] = 35*4;
mbox[1] = MBOX_REQUEST;
mbox[2] = 0x48003; //set phy wh
mbox[3] = 8;
mbox[4] = 8;
mbox[5] = FBWIDTH; //FrameBufferInfo.width
mbox[6] = FBHEIGHT; //FrameBufferInfo.height
mbox[7] = 0x48004; //set virt wh
mbox[8] = 8;
mbox[9] = 8;
mbox[10] = FBWIDTH;//FrameBufferInfo.virtual_width
mbox[11] = FBHEIGHT * 2; //FrameBufferInfo.virtual_height
mbox[12] = 0x48009; //set virt offset
mbox[13] = 8;
mbox[14] = 8;
mbox[15] = 0; //FrameBufferInfo.x_offset
mbox[16] = 0; //FrameBufferInfo.y.offset
mbox[17] = 0x48005; //set depth
mbox[18] = 4;
mbox[19] = 4;
mbox[20] = 32; //FrameBufferInfo.depth
mbox[21] = 0x48006; //set pixel order
mbox[22] = 4;
mbox[23] = 4;
mbox[24] = 1; //RGB, not BGR preferably
mbox[25] = 0x40001; //get framebuffer, gets alignment on request
mbox[26] = 8;
mbox[27] = 8;
mbox[28] = 4096;//FrameBufferInfo.pointer
mbox[29] = 0; //FrameBufferInfo.size
mbox[30] = 0x40008; //get pitch
mbox[31] = 4;
mbox[32] = 4;
mbox[33] = 0; //FrameBufferInfo.pitch
mbox[34] = MBOX_TAG_LAST;
if(mbox_call(MBOX_CH_PROP) && mbox[20]==32 && mbox[28]!=0) {
mbox[28]&=0x3FFF;
fbwidth=mbox[5];
fbheight=mbox[6];
pitch=mbox[33];
lfb=(void*)((unsigned long)mbox[28]);
}
}
I will assume, for the sake of this posting, that the reader
understands the mailbox architecture and the appropriate address
definitions for them. The key point is that allocating a virtual
buffer twice the height of the physical buffer results in QEMU
improperly displaying a double-height window.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1777672/+subscriptions
[Qemu-devel] [Bug 1777672] Re: QEMU aarch64 virtual/physical frame buffer
The virtual size must be at least the size of the physical display. One
approach toward double-buffering is to make the virtual height twice the
physical height. To "flip" the displays you simply change the start of
the visible view port.
See these:
https://lb.raspberrypi.org/forums/viewtopic.php?t=47329
https://www.raspberrypi.org/forums/viewtopic.php?f=67&t=19073&p=324866#p324866
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1777672
Title:
QEMU aarch64 virtual/physical frame buffer
Status in QEMU:
New
Bug description:
I fully recognize that the error here could be mine, but the code is
pretty simple and straightforward; When emulating a Raspberry PI 3
using aarch64 and allocating a virtual framebuffer larger than the
physical frambuffer (for double-buffering purposes), the QEMU window
shows the full size of the *virtual* framebuffer rather than the size
of the *physical* framebuffer.
You can replicate this with code such as:
#define FBWIDTH 1024
#define FBHEIGHT 768
void lfb_init()
{
uart_puts("Initializing Framebuffer\n");
mbox[0] = 35*4;
mbox[1] = MBOX_REQUEST;
mbox[2] = 0x48003; //set phy wh
mbox[3] = 8;
mbox[4] = 8;
mbox[5] = FBWIDTH; //FrameBufferInfo.width
mbox[6] = FBHEIGHT; //FrameBufferInfo.height
mbox[7] = 0x48004; //set virt wh
mbox[8] = 8;
mbox[9] = 8;
mbox[10] = FBWIDTH;//FrameBufferInfo.virtual_width
mbox[11] = FBHEIGHT * 2; //FrameBufferInfo.virtual_height
mbox[12] = 0x48009; //set virt offset
mbox[13] = 8;
mbox[14] = 8;
mbox[15] = 0; //FrameBufferInfo.x_offset
mbox[16] = 0; //FrameBufferInfo.y.offset
mbox[17] = 0x48005; //set depth
mbox[18] = 4;
mbox[19] = 4;
mbox[20] = 32; //FrameBufferInfo.depth
mbox[21] = 0x48006; //set pixel order
mbox[22] = 4;
mbox[23] = 4;
mbox[24] = 1; //RGB, not BGR preferably
mbox[25] = 0x40001; //get framebuffer, gets alignment on request
mbox[26] = 8;
mbox[27] = 8;
mbox[28] = 4096;//FrameBufferInfo.pointer
mbox[29] = 0; //FrameBufferInfo.size
mbox[30] = 0x40008; //get pitch
mbox[31] = 4;
mbox[32] = 4;
mbox[33] = 0; //FrameBufferInfo.pitch
mbox[34] = MBOX_TAG_LAST;
if(mbox_call(MBOX_CH_PROP) && mbox[20]==32 && mbox[28]!=0) {
mbox[28]&=0x3FFF;
fbwidth=mbox[5];
fbheight=mbox[6];
pitch=mbox[33];
lfb=(void*)((unsigned long)mbox[28]);
}
}
I will assume, for the sake of this posting, that the reader
understands the mailbox architecture and the appropriate address
definitions for them. The key point is that allocating a virtual
buffer twice the height of the physical buffer results in QEMU
improperly displaying a double-height window.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1777672/+subscriptions
[Qemu-devel] [Bug 1777672] Re: QEMU aarch64 virtual/physical frame buffer
Thanks for the test case. I'm having difficulty matching up your guest
code with the documentation of the fb mbox tags in
https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
...
Your code sets the physical height to FBHEIGHT via tag 0x48003, and the
virtual height to FBHEIGHT * 2 via tag 0x48004. The documentation in the
wiki link agrees that 48003 is phys w/h and 48004 is virt w/h, but it
says that the physical size is the size of the buffer in memory, and the
virtual size is the size of the viewport sent to the display device, ie
the virtual size should be smaller than the physical, not vice-versa.
Which is correct ?
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1777672
Title:
QEMU aarch64 virtual/physical frame buffer
Status in QEMU:
New
Bug description:
I fully recognize that the error here could be mine, but the code is
pretty simple and straightforward; When emulating a Raspberry PI 3
using aarch64 and allocating a virtual framebuffer larger than the
physical frambuffer (for double-buffering purposes), the QEMU window
shows the full size of the *virtual* framebuffer rather than the size
of the *physical* framebuffer.
You can replicate this with code such as:
#define FBWIDTH 1024
#define FBHEIGHT 768
void lfb_init()
{
uart_puts("Initializing Framebuffer\n");
mbox[0] = 35*4;
mbox[1] = MBOX_REQUEST;
mbox[2] = 0x48003; //set phy wh
mbox[3] = 8;
mbox[4] = 8;
mbox[5] = FBWIDTH; //FrameBufferInfo.width
mbox[6] = FBHEIGHT; //FrameBufferInfo.height
mbox[7] = 0x48004; //set virt wh
mbox[8] = 8;
mbox[9] = 8;
mbox[10] = FBWIDTH;//FrameBufferInfo.virtual_width
mbox[11] = FBHEIGHT * 2; //FrameBufferInfo.virtual_height
mbox[12] = 0x48009; //set virt offset
mbox[13] = 8;
mbox[14] = 8;
mbox[15] = 0; //FrameBufferInfo.x_offset
mbox[16] = 0; //FrameBufferInfo.y.offset
mbox[17] = 0x48005; //set depth
mbox[18] = 4;
mbox[19] = 4;
mbox[20] = 32; //FrameBufferInfo.depth
mbox[21] = 0x48006; //set pixel order
mbox[22] = 4;
mbox[23] = 4;
mbox[24] = 1; //RGB, not BGR preferably
mbox[25] = 0x40001; //get framebuffer, gets alignment on request
mbox[26] = 8;
mbox[27] = 8;
mbox[28] = 4096;//FrameBufferInfo.pointer
mbox[29] = 0; //FrameBufferInfo.size
mbox[30] = 0x40008; //get pitch
mbox[31] = 4;
mbox[32] = 4;
mbox[33] = 0; //FrameBufferInfo.pitch
mbox[34] = MBOX_TAG_LAST;
if(mbox_call(MBOX_CH_PROP) && mbox[20]==32 && mbox[28]!=0) {
mbox[28]&=0x3FFF;
fbwidth=mbox[5];
fbheight=mbox[6];
pitch=mbox[33];
lfb=(void*)((unsigned long)mbox[28]);
}
}
I will assume, for the sake of this posting, that the reader
understands the mailbox architecture and the appropriate address
definitions for them. The key point is that allocating a virtual
buffer twice the height of the physical buffer results in QEMU
improperly displaying a double-height window.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1777672/+subscriptions
[Qemu-devel] [Bug 1777672] Re: QEMU aarch64 virtual/physical frame buffer
Whoops.. Forgot to include the QEMU command line:
qemu-system-aarch64 -M raspi3 --kernel kernel8.img -serial stdio
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1777672
Title:
QEMU aarch64 virtual/physical frame buffer
Status in QEMU:
New
Bug description:
I fully recognize that the error here could be mine, but the code is
pretty simple and straightforward; When emulating a Raspberry PI 3
using aarch64 and allocating a virtual framebuffer larger than the
physical frambuffer (for double-buffering purposes), the QEMU window
shows the full size of the *virtual* framebuffer rather than the size
of the *physical* framebuffer.
You can replicate this with code such as:
#define FBWIDTH 1024
#define FBHEIGHT 768
void lfb_init()
{
uart_puts("Initializing Framebuffer\n");
mbox[0] = 35*4;
mbox[1] = MBOX_REQUEST;
mbox[2] = 0x48003; //set phy wh
mbox[3] = 8;
mbox[4] = 8;
mbox[5] = FBWIDTH; //FrameBufferInfo.width
mbox[6] = FBHEIGHT; //FrameBufferInfo.height
mbox[7] = 0x48004; //set virt wh
mbox[8] = 8;
mbox[9] = 8;
mbox[10] = FBWIDTH;//FrameBufferInfo.virtual_width
mbox[11] = FBHEIGHT * 2; //FrameBufferInfo.virtual_height
mbox[12] = 0x48009; //set virt offset
mbox[13] = 8;
mbox[14] = 8;
mbox[15] = 0; //FrameBufferInfo.x_offset
mbox[16] = 0; //FrameBufferInfo.y.offset
mbox[17] = 0x48005; //set depth
mbox[18] = 4;
mbox[19] = 4;
mbox[20] = 32; //FrameBufferInfo.depth
mbox[21] = 0x48006; //set pixel order
mbox[22] = 4;
mbox[23] = 4;
mbox[24] = 1; //RGB, not BGR preferably
mbox[25] = 0x40001; //get framebuffer, gets alignment on request
mbox[26] = 8;
mbox[27] = 8;
mbox[28] = 4096;//FrameBufferInfo.pointer
mbox[29] = 0; //FrameBufferInfo.size
mbox[30] = 0x40008; //get pitch
mbox[31] = 4;
mbox[32] = 4;
mbox[33] = 0; //FrameBufferInfo.pitch
mbox[34] = MBOX_TAG_LAST;
if(mbox_call(MBOX_CH_PROP) && mbox[20]==32 && mbox[28]!=0) {
mbox[28]&=0x3FFF;
fbwidth=mbox[5];
fbheight=mbox[6];
pitch=mbox[33];
lfb=(void*)((unsigned long)mbox[28]);
}
}
I will assume, for the sake of this posting, that the reader
understands the mailbox architecture and the appropriate address
definitions for them. The key point is that allocating a virtual
buffer twice the height of the physical buffer results in QEMU
improperly displaying a double-height window.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1777672/+subscriptions
[Qemu-devel] [Bug 1777672] Re: QEMU aarch64 virtual/physical frame buffer
Certainly! Attached.
If you start the attached on a piece of hardware, it will start and display
fine.. If you start it in QEMU, it will start but display a double-height
screen rather than limiting the physical screen to the specified dimensions.
(The virtual display is double-height in preparation for double
buffering)
** Attachment added: "kernel8.img"
https://bugs.launchpad.net/qemu/+bug/1777672/+attachment/5168270/+files/kernel8.img
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1777672
Title:
QEMU aarch64 virtual/physical frame buffer
Status in QEMU:
New
Bug description:
I fully recognize that the error here could be mine, but the code is
pretty simple and straightforward; When emulating a Raspberry PI 3
using aarch64 and allocating a virtual framebuffer larger than the
physical frambuffer (for double-buffering purposes), the QEMU window
shows the full size of the *virtual* framebuffer rather than the size
of the *physical* framebuffer.
You can replicate this with code such as:
#define FBWIDTH 1024
#define FBHEIGHT 768
void lfb_init()
{
uart_puts("Initializing Framebuffer\n");
mbox[0] = 35*4;
mbox[1] = MBOX_REQUEST;
mbox[2] = 0x48003; //set phy wh
mbox[3] = 8;
mbox[4] = 8;
mbox[5] = FBWIDTH; //FrameBufferInfo.width
mbox[6] = FBHEIGHT; //FrameBufferInfo.height
mbox[7] = 0x48004; //set virt wh
mbox[8] = 8;
mbox[9] = 8;
mbox[10] = FBWIDTH;//FrameBufferInfo.virtual_width
mbox[11] = FBHEIGHT * 2; //FrameBufferInfo.virtual_height
mbox[12] = 0x48009; //set virt offset
mbox[13] = 8;
mbox[14] = 8;
mbox[15] = 0; //FrameBufferInfo.x_offset
mbox[16] = 0; //FrameBufferInfo.y.offset
mbox[17] = 0x48005; //set depth
mbox[18] = 4;
mbox[19] = 4;
mbox[20] = 32; //FrameBufferInfo.depth
mbox[21] = 0x48006; //set pixel order
mbox[22] = 4;
mbox[23] = 4;
mbox[24] = 1; //RGB, not BGR preferably
mbox[25] = 0x40001; //get framebuffer, gets alignment on request
mbox[26] = 8;
mbox[27] = 8;
mbox[28] = 4096;//FrameBufferInfo.pointer
mbox[29] = 0; //FrameBufferInfo.size
mbox[30] = 0x40008; //get pitch
mbox[31] = 4;
mbox[32] = 4;
mbox[33] = 0; //FrameBufferInfo.pitch
mbox[34] = MBOX_TAG_LAST;
if(mbox_call(MBOX_CH_PROP) && mbox[20]==32 && mbox[28]!=0) {
mbox[28]&=0x3FFF;
fbwidth=mbox[5];
fbheight=mbox[6];
pitch=mbox[33];
lfb=(void*)((unsigned long)mbox[28]);
}
}
I will assume, for the sake of this posting, that the reader
understands the mailbox architecture and the appropriate address
definitions for them. The key point is that allocating a virtual
buffer twice the height of the physical buffer results in QEMU
improperly displaying a double-height window.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1777672/+subscriptions
[Qemu-devel] [Bug 1777672] Re: QEMU aarch64 virtual/physical frame buffer
Can you provide a test binary and QEMU command line that reproduce this,
please ?
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1777672
Title:
QEMU aarch64 virtual/physical frame buffer
Status in QEMU:
New
Bug description:
I fully recognize that the error here could be mine, but the code is
pretty simple and straightforward; When emulating a Raspberry PI 3
using aarch64 and allocating a virtual framebuffer larger than the
physical frambuffer (for double-buffering purposes), the QEMU window
shows the full size of the *virtual* framebuffer rather than the size
of the *physical* framebuffer.
You can replicate this with code such as:
#define FBWIDTH 1024
#define FBHEIGHT 768
void lfb_init()
{
uart_puts("Initializing Framebuffer\n");
mbox[0] = 35*4;
mbox[1] = MBOX_REQUEST;
mbox[2] = 0x48003; //set phy wh
mbox[3] = 8;
mbox[4] = 8;
mbox[5] = FBWIDTH; //FrameBufferInfo.width
mbox[6] = FBHEIGHT; //FrameBufferInfo.height
mbox[7] = 0x48004; //set virt wh
mbox[8] = 8;
mbox[9] = 8;
mbox[10] = FBWIDTH;//FrameBufferInfo.virtual_width
mbox[11] = FBHEIGHT * 2; //FrameBufferInfo.virtual_height
mbox[12] = 0x48009; //set virt offset
mbox[13] = 8;
mbox[14] = 8;
mbox[15] = 0; //FrameBufferInfo.x_offset
mbox[16] = 0; //FrameBufferInfo.y.offset
mbox[17] = 0x48005; //set depth
mbox[18] = 4;
mbox[19] = 4;
mbox[20] = 32; //FrameBufferInfo.depth
mbox[21] = 0x48006; //set pixel order
mbox[22] = 4;
mbox[23] = 4;
mbox[24] = 1; //RGB, not BGR preferably
mbox[25] = 0x40001; //get framebuffer, gets alignment on request
mbox[26] = 8;
mbox[27] = 8;
mbox[28] = 4096;//FrameBufferInfo.pointer
mbox[29] = 0; //FrameBufferInfo.size
mbox[30] = 0x40008; //get pitch
mbox[31] = 4;
mbox[32] = 4;
mbox[33] = 0; //FrameBufferInfo.pitch
mbox[34] = MBOX_TAG_LAST;
if(mbox_call(MBOX_CH_PROP) && mbox[20]==32 && mbox[28]!=0) {
mbox[28]&=0x3FFF;
fbwidth=mbox[5];
fbheight=mbox[6];
pitch=mbox[33];
lfb=(void*)((unsigned long)mbox[28]);
}
}
I will assume, for the sake of this posting, that the reader
understands the mailbox architecture and the appropriate address
definitions for them. The key point is that allocating a virtual
buffer twice the height of the physical buffer results in QEMU
improperly displaying a double-height window.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1777672/+subscriptions
[Qemu-devel] [Bug 1777672] Re: QEMU aarch64 virtual/physical frame buffer
** Tags added: arm
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1777672
Title:
QEMU aarch64 virtual/physical frame buffer
Status in QEMU:
New
Bug description:
I fully recognize that the error here could be mine, but the code is
pretty simple and straightforward; When emulating a Raspberry PI 3
using aarch64 and allocating a virtual framebuffer larger than the
physical frambuffer (for double-buffering purposes), the QEMU window
shows the full size of the *virtual* framebuffer rather than the size
of the *physical* framebuffer.
You can replicate this with code such as:
#define FBWIDTH 1024
#define FBHEIGHT 768
void lfb_init()
{
uart_puts("Initializing Framebuffer\n");
mbox[0] = 35*4;
mbox[1] = MBOX_REQUEST;
mbox[2] = 0x48003; //set phy wh
mbox[3] = 8;
mbox[4] = 8;
mbox[5] = FBWIDTH; //FrameBufferInfo.width
mbox[6] = FBHEIGHT; //FrameBufferInfo.height
mbox[7] = 0x48004; //set virt wh
mbox[8] = 8;
mbox[9] = 8;
mbox[10] = FBWIDTH;//FrameBufferInfo.virtual_width
mbox[11] = FBHEIGHT * 2; //FrameBufferInfo.virtual_height
mbox[12] = 0x48009; //set virt offset
mbox[13] = 8;
mbox[14] = 8;
mbox[15] = 0; //FrameBufferInfo.x_offset
mbox[16] = 0; //FrameBufferInfo.y.offset
mbox[17] = 0x48005; //set depth
mbox[18] = 4;
mbox[19] = 4;
mbox[20] = 32; //FrameBufferInfo.depth
mbox[21] = 0x48006; //set pixel order
mbox[22] = 4;
mbox[23] = 4;
mbox[24] = 1; //RGB, not BGR preferably
mbox[25] = 0x40001; //get framebuffer, gets alignment on request
mbox[26] = 8;
mbox[27] = 8;
mbox[28] = 4096;//FrameBufferInfo.pointer
mbox[29] = 0; //FrameBufferInfo.size
mbox[30] = 0x40008; //get pitch
mbox[31] = 4;
mbox[32] = 4;
mbox[33] = 0; //FrameBufferInfo.pitch
mbox[34] = MBOX_TAG_LAST;
if(mbox_call(MBOX_CH_PROP) && mbox[20]==32 && mbox[28]!=0) {
mbox[28]&=0x3FFF;
fbwidth=mbox[5];
fbheight=mbox[6];
pitch=mbox[33];
lfb=(void*)((unsigned long)mbox[28]);
}
}
I will assume, for the sake of this posting, that the reader
understands the mailbox architecture and the appropriate address
definitions for them. The key point is that allocating a virtual
buffer twice the height of the physical buffer results in QEMU
improperly displaying a double-height window.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1777672/+subscriptions
