[AMD Official Use Only - Internal Distribution Only]
>And we already checked, 256MB is unfortunately the minimum you can resize the VRAM BAR on the E9171 to.
Ahh, OK... I didn't realize we had already looked into that. I guess that approach isn't going to work.
Yusef, guessing you are using a 32-bit CPU ? Is it possible to talk to whoever does SBIOS for your platform to see if you could maybe reduce address space allocated to RAM and bump up the MMIO space ?
From: Christian König <ckoenig.leichtzumerken@xxxxxxxxx>
Sent: February 18, 2020 9:19 AM To: Bridgman, John <John.Bridgman@xxxxxxx>; Alex Deucher <alexdeucher@xxxxxxxxx>; Yusuf Altıparmak <yusufalti1997@xxxxxxxxx> Cc: amd-gfx list <amd-gfx@xxxxxxxxxxxxxxxxxxxxx> Subject: Re: writing custom driver for VGA emulation ? The problem Yusuf runs into is that his platform has multiple PCIe root hubs, but only 512MB of MMIO address space. That is not enough to fit all the BARs of an E9171 into.
But without the BARs neither the VGA emulation nor amdgpu not anything else will work correctly. And we already checked, 256MB is unfortunately the minimum you can resize the VRAM BAR on the E9171 to. What could maybe work is to trick the upstream bridge of the VGA device into not routing all the addresses to the BARs and actually use only a smaller portion of visible VRAM. But that would be highly experimental and requires a rather big hack into the PCI(e) subsystem in the Linux kernel. Regards, Christian. Am 18.02.20 um 15:08 schrieb Bridgman, John:
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