Re: amdgpu RX6800 crashes kernel during startx

On Sun, Jun 14, 2026 at 09:52:53PM +0300, Petre Rodan wrote:
>  9:0:0: ATI Navi 21
> 	0x0000: Vendor ID: 1002, Product ID: 73bf
> 	0x0004: Command: 0006, Status: 0010
> 	0x0008:	Class: 03 Display, Subclass: 00 VGA,
> 		Interface: 00, Revision: c3
> 	0x000c: BIST: 00, Header Type: 80, Latency Timer: 00,
> 		Cache Line Size: 10
> 	0x0010: BAR mem prefetchable 64bit addr: 0x0000007800000000/0x400000000
> 	0x0018: BAR mem prefetchable 64bit addr: 0x0000007c00000000/0x10000000
> 	0x0020: BAR io addr: 0x0000e000/0x0100
> 	0x0024: BAR mem 32bit addr: 0xfca00000/0x00100000

framebuffer memory is described by pci bar 0x10

the window size here is already 16GB, even without resizing the bar

can you try this diff to force visible vram to 512MB?

Index: sys/dev/pci/drm/amd/amdgpu/amdgpu_gmc.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/drm/amd/amdgpu/amdgpu_gmc.c,v
diff -u -p -r1.20 amdgpu_gmc.c
--- sys/dev/pci/drm/amd/amdgpu/amdgpu_gmc.c	25 May 2026 08:56:32 -0000	1.20
+++ sys/dev/pci/drm/amd/amdgpu/amdgpu_gmc.c	15 Jun 2026 03:53:34 -0000
@@ -216,6 +216,8 @@ void amdgpu_gmc_vram_location(struct amd
 	uint64_t vis_limit = (uint64_t)amdgpu_vis_vram_limit << 20;
 	uint64_t limit = (uint64_t)amdgpu_vram_limit << 20;
 
+	vis_limit = 512ULL << 20;
+
 	mc->vram_start = base;
 	mc->vram_end = mc->vram_start + mc->mc_vram_size - 1;
 	if (limit < mc->real_vram_size)