elementary OS 0.4.1 Loki vs Apple iMac mid 2007 entorn gràfic

He tingut bastants problemes amb la tarjeta gràfica del iMac amb el elementary OS

Apple Inc. iMac7,1/Mac-F4238CC8, BIOS     IM71.88Z.007A.B03.0803051705 03/05/08
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RV610/M74 [Mobility Radeon HD 2400 XT] (prog-if 00 [VGA controller])
	Subsystem: Apple Inc. RV610/M74 [Mobility Radeon HD 2400 XT]
	Physical Slot: 1
	Flags: bus master, fast devsel, latency 0
	Memory at c0000000 (64-bit, prefetchable) [size=256M]
	Memory at d0620000 (64-bit, non-prefetchable) [size=64K]
	I/O ports at 3000 [size=256]
	Expansion ROM at d0600000 [disabled] [size=128K]
	Capabilities: [50] Power Management version 3
	Capabilities: [58] Express Legacy Endpoint, MSI 00
	Capabilities: [a0] MSI: Enable- Count=1/1 Maskable- 64bit+
	Capabilities: [100] Vendor Specific Information: ID=0001 Rev=1 Len=010 <!--?-->
	Kernel modules: radeon

El problemes bàsicament és que l’entorn gràfic a cap d’una estona posava amb una pantalla amb ratlles o en negre sense poder-se recuperar.

La consola enviava els següents missatges:

[ 1779.528311] [drm] ib test on ring 0 succeeded in 0 usecs
[ 1780.700155] [drm:uvd_v1_0_ib_test [radeon]] *ERROR* radeon: fence wait timed out.
[ 1780.700200] [drm:radeon_ib_ring_tests [radeon]] *ERROR* radeon: failed testing IB on ring 5 (-110).
[ 1790.812114] radeon 0000:01:00.0: ring 0 stalled for more than 10104msec
[ 1790.812130] radeon 0000:01:00.0: GPU lockup (current fence id 0x00000000000165f5 last fence id 0x0000000000016610 on ring 0)
[ 1791.324128] radeon 0000:01:00.0: ring 0 stalled for more than 10616msec
[ 1791.324144] radeon 0000:01:00.0: GPU lockup (current fence id 0x00000000000165f5 last fence id 0x0000000000016610 on ring 0)
[ 1791.836099] radeon 0000:01:00.0: ring 0 stalled for more than 11128msec
[ 1791.836110] radeon 0000:01:00.0: GPU lockup (current fence id 0x00000000000165f5 last fence id 0x0000000000016610 on ring 0)
[ 1792.348125] radeon 0000:01:00.0: ring 0 stalled for more than 11640msec
[ 1792.348139] radeon 0000:01:00.0: GPU lockup (current fence id 0x00000000000165f5 last fence id 0x0000000000016610 on ring 0)

Després de llegir bastant pel Google finalment he decidit posar una paràmetre per deshabilitat el FB de la tarja gràfica.

Normalment sempre he posat vga=normal però en aquest cas he posat nomodeset en les opcions del grub.

Com a usuari ‘root’:

sed -i "s/GRUB_CMDLINE_LINUX_DEFAULT=.*/GRUB_CMDLINE_LINUX_DEFAULT=\"nomodeset\"/g" /etc/default/grub
update-grub
cat /proc/cmdline 
BOOT_IMAGE=/boot/vmlinuz-4.10.0-37-generic.efi.signed root=UUID=dcca0165-b9f7-41b2-ac6e-9d4d73386794 ro nomodeset