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[Success] Radeon RX 6800 XT - Big Sur

Gigamaxx

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Removing the rom-revision unfortunately does not make a difference.
I did try spoofing via DeviceProperties before and it didn't work back then, either, so this is not surprising, I suppose.
It's strange, since I *can* modify other parts of the device's properties, such as APPL,slot-name and the like, but the device-id property has thus far never changed, no matter what.

I was able to use GPU-Z to dump the VBIOS finally (thanks to the latest update) but it's been available on the VBIOS list on TechPowerUP for a while anyway. If anybody wants to mess around with it, feel free to. The attached file is the default VBIOS of the Liquid Devil Ultimate 6900 XT.
Please test these. Slot is still #1 edit if needed.
 

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Please test these. Slot is still #1 edit if needed.
No change, unfortunately. Casey and I already tried the FakePCIID route a bit earlier on as well, with the same result.
The RM,device-id property does attach, but the actual device-id refuses to change.

Since I was able to dump the VBIOS of my GPU now, I've modified the ID in there with a hex editor. I will likely attempt to flash this customized version once I have some time to toy around with this on Windows. Since the card has a Dual-VBIOS, this should be relatively safe, as I can always recover.
 

CaseySJ

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No change, unfortunately. Casey and I already tried the FakePCIID route a bit earlier on as well, with the same result.
The RM,device-id property does attach, but the actual device-id refuses to change.

Since I was able to dump the VBIOS of my GPU now, I've modified the ID in there with a hex editor. I will likely attempt to flash this customized version once I have some time to toy around with this on Windows. Since the card has a Dual-VBIOS, this should be relatively safe, as I can always recover.
A VBIOS mod appears to be the most promising option at this time. Waiting with bated breath…
 
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Since I was able to dump the VBIOS of my GPU now, I've modified the ID in there with a hex editor. I will likely attempt to flash this customized version once I have some time to toy around with this on Windows. Since the card has a Dual-VBIOS, this should be relatively safe, as I can always recover.
You shouldn't need to use a hex editor to change the device-id of the GPU. You should only need to re-flash the GPU with the option `-padevid=<ID>` in the command. Make sure to check the help command for ATIFlash.

Example:
Code:
AtiFlash.exe -f -pa -padevid=73bf 0 newenhancedbios.rom
 
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You shouldn't need to use a hex editor to change the device-id of the GPU. You should only need to re-flash the GPU with the option `-padevid=<ID>` in the command. Make sure to check the help command for ATIFlash.

Example:
Code:
AtiFlash.exe -f -pa -padevid=73bf 0 newenhancedbios.rom
I believe you may have confused what these arguments do here.
According to the help text, invoking atiflash with -pa and -padevid governs which devices the VBIOS is written to.
It does not, however, modify anything about the card itself, as these arguments are simply selectors so you can more easily target which devices you want to flash.
To modify anything inside the VBIOS, you will still need to hex-edit it (or use a GUI editor provided some kind soul has already reverse-engineered the various settings).

Invoking this with an XTXH card in the system will not flash anything, because -padevid=73bf targets cards with a different ID (specifically, the "normal" 6900 XT's). If anything, it should be set to 73af, which will actually target the correct card.

Unfortunately however, ATIFlash 3.15 is the latest version that is currently available. It is also the case that 3.15 does not support the XTXH cards yet, only the regular 6900 XT and its smaller brethren. As such, even though I already have the modified VBIOS, I am currently unable to flash it.

This is also partially due to the fact that none of the public versions of ATIFlash provide the "-f" flag (which forces flashing even if the card is unknown). Unless somebody here has access to a version of ATIFlash with this flag and is willing to share it with me, this is as far as I can go for the time being.

As soon as a new version of ATIFlash becomes available, I'll try the VBIOS mod.

EDIT: It appears that the linux version of this tool *may* allow force flashing but the Windows version doesn't. Alas, it seems the Linux version hasn't been updated since August 2019, so I'm not sure whether this actually supports the new cards at all.
I will set up a Linux Live USB and I'll give that a shot next.
 
Last edited:

CaseySJ

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@byteminer,

Ouch, roadblocks everywhere. Have you considered auctioning off the card and doing the NewEgg shuffle? ;)
 
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Nah, I ain't giving up that easily :)

On that note: Progress!
On Linux, atiflash actually recognizes the XTXH card properly, device ID, VBIOS version and all, so I'm a bit more hopeful now.

I'm gonna transfer my modified VBIOS over to the live image and I'll attempt a flash tonight.
 
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In my tests I tried HEX changing the ID on a WX-4170 ROM and it didn't actually change how the drivers see the card.
So there must be another not-so-obvious spot where the ROM has this device-id.
If I flashed a completely different ROM, then the device-id changed with the new ROM, so it is definitely there, but it's not just the data after PCIR and/or in the GOP section.
 
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I believe you may have confused what these arguments do here.
According to the help text, invoking atiflash with -pa and -padevid governs which devices the VBIOS is written to.
It does not, however, modify anything about the card itself, as these arguments are simply selectors so you can more easily target which devices you want to flash.
To modify anything inside the VBIOS, you will still need to hex-edit it (or use a GUI editor provided some kind soul has already reverse-engineered the various settings).

Invoking this with an XTXH card in the system will not flash anything, because -padevid=73bf targets cards with a different ID (specifically, the "normal" 6900 XT's). If anything, it should be set to 73af, which will actually target the correct card.

Unfortunately however, ATIFlash 3.15 is the latest version that is currently available. It is also the case that 3.15 does not support the XTXH cards yet, only the regular 6900 XT and its smaller brethren. As such, even though I already have the modified VBIOS, I am currently unable to flash it.

This is also partially due to the fact that none of the public versions of ATIFlash provide the "-f" flag (which forces flashing even if the card is unknown). Unless somebody here has access to a version of ATIFlash with this flag and is willing to share it with me, this is as far as I can go for the time being.

As soon as a new version of ATIFlash becomes available, I'll try the VBIOS mod.

EDIT: It appears that the linux version of this tool *may* allow force flashing but the Windows version doesn't. Alas, it seems the Linux version hasn't been updated since August 2019, so I'm not sure whether this actually supports the new cards at all.
I will set up a Linux Live USB and I'll give that a shot next.
Guess I read it wrong, my bad but you should still be able to do it with the `-mb` option.
Code:
-mb <Num> <File>        Modify SSID, SVID, BIOS Pin Number, & Boot Message in
                        BIOS image of adapter <Num> to values in <filename>.
                        Input file example:
                           ssid = 715B
                           svid = 1002
                           biospn = "113-xxxxxx-xx"
                           bootmsg = "ATI graphic board"
 
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Didn't think I would get it that easily. Debating if I should pull the trigger since I dont really need it :lol:

Screen Shot 2021-05-13 at 2.02.28 PM.png
 
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