On Sun, 5 Jun 2016, Michael van Elst wrote:
On Sat, Jun 04, 2016 at 04:15:15PM +0100, Stephen Borrill wrote:
Under Windows it is cool and I get 6-hour battery life...
Does it have an ATI graphics card and also Intel graphics?
Yes. And that's the root of the hanging problem.
If Integrated graphics (Intel) or Discrete graphics (ATI) are selected in the
BIOS, the machine boots.
With Intel, DRM attaches very early on:
pci0 at mainbus0 bus 0: configuration mode 1
pci0: i/o space, memory space enabled, rd/line, rd/mult, wr/inv ok
pchb0 at pci0 dev 0 function 0: vendor 0x8086 product 0x2a40 (rev. 0x07)
agp0 at pchb0: G4X-family chipset
agp0: detected 32252k stolen memory
agp0: aperture at 0xd0000000, size 0x10000000
i915drmkms0 at pci0 dev 2 function 0: vendor 0x8086 product 0x2a42 (rev.
0x07)
drm: Memory usable by graphics device = 512M
drm: Supports vblank timestamp caching Rev 2 (21.10.2013).
drm: Driver supports precise vblank timestamp query.
i915drmkms0: interrupting at ioapic0 pin 16 (i915)
intelfb0 at i915drmkms0
i915drmkms0: info: registered panic notifier
With ATI, DRM attaches much, much later on:
pad0: outputs: 44100Hz, 16-bit, stereo
audio1 at pad0: half duplex, playback, capture
boot device: wd0
root on wd0a dumps on wd0b
root file system type: ffs
drm: initializing kernel modesetting (RV635 0x1002:0x9591 0x17AA:0x2117).
drm: register mmio base: 0xcfff0000
drm: register mmio size: 65536
drm kern info: ATOM BIOS: M86M
radeon0: info: VRAM: 256M 0x0000000000000000 - 0x000000000FFFFFFF (256M used)
radeon0: info: GTT: 512M 0x0000000010000000 - 0x000000002FFFFFFF
Note that this is around the point where the machine hangs. If Switchable
graphics is enabled in the BIOS (which is the default it likes to keep
resetting back to), the hang occurs. My theory is that i915drmkms0 attaches
early and then the later probe for radeon0 (and perhaps even trying to double
up on DRM?) is causing the hang. When the device is hidden or disabled by the
BIOS, it is OK.
Between RC2 (OK) and RC3 (hang) there were a number of changes to the radeon
and i915 drm code. Not had chance to test which yet.