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klange wrote:Under the menu labeled 视图, can you select "compatmonitor0", enter the command "info tlb", and post the results?

klange wrote:It does look like you are successfully mapping 0xFD000000, but I suspect that QEMU is ignoring either your writes or your reads to the region since you don't actually have a framebuffer set up. It's also possible something is going wrong with your pointer code - native C# stuff is a mysterious black box to me.

klange wrote:It does look like you are successfully mapping 0xFD000000, but I suspect that QEMU is ignoring either your writes or your reads to the region since you don't actually have a framebuffer set up. It's also possible something is going wrong with your pointer code - native C# stuff is a mysterious black box to me.

linuxyne wrote:Is the frame buffer mapped as cached, write-back? What if you try to write to it before/without enabling the paging?

Edit: The top-left corner of the VM display, before and after "set {char}0xfd000000=0xaa" from gdb:

Before:


After:

klange wrote:It does look like you are successfully mapping 0xFD000000, but I suspect that QEMU is ignoring either your writes or your reads to the region since you don't actually have a framebuffer set up. It's also possible something is going wrong with your pointer code - native C# stuff is a mysterious black box to me.

Invalid access at addr 0xE0000000, size 8, region '(null)', reason: rejected

nifanfa wrote:when i enable qemu debug and write to 0xe0000000 it displays

Code: Select all

Invalid access at addr 0xE0000000, size 8, region '(null)', reason: rejected

Octocontrabass wrote:

nifanfa wrote:when i enable qemu debug and write to 0xe0000000 it displays

Code: Select all

Invalid access at addr 0xE0000000, size 8, region '(null)', reason: rejected

This error means you have mapped that address correctly in your page tables, but QEMU is ignoring your reads and writes because there's nothing at that address.

It sounds like your code to map the page tables works fine. You don't see anything appear when you write to the linear frame buffer because there is no linear frame buffer in text mode.

nifanfa wrote:

Octocontrabass wrote:

nifanfa wrote:when i enable qemu debug and write to 0xe0000000 it displays

Code: Select all

Invalid access at addr 0xE0000000, size 8, region '(null)', reason: rejected

This error means you have mapped that address correctly in your page tables, but QEMU is ignoring your reads and writes because there's nothing at that address.

It sounds like your code to map the page tables works fine. You don't see anything appear when you write to the linear frame buffer because there is no linear frame buffer in text mode.

Octocontrabass wrote:What happens if you use the framebuffer address provided by your bootloader instead of 0xFD000000?

Octocontrabass wrote:Are you halting the CPU after you write to the framebuffer? Some versions of QEMU will not display screen updates that happen shortly before the CPU halts.

What type of framebuffer did you request in your multiboot header?

Invalid access at addr 0xFD000000, size 8, region '(null)', reason: rejected

Octocontrabass wrote:Are you halting the CPU after you write to the framebuffer? Some versions of QEMU will not display screen updates that happen shortly before the CPU halts.

What type of framebuffer did you request in your multiboot header?