FS#40899 - [linux] Unable to boot with Intel i915 driver/hardware
Attached to Project:
Arch Linux
Opened by Markus Enax (mnx) - Thursday, 19 June 2014, 19:16 GMT
Last edited by Tobias Powalowski (tpowa) - Wednesday, 13 August 2014, 18:07 GMT
Opened by Markus Enax (mnx) - Thursday, 19 June 2014, 19:16 GMT
Last edited by Tobias Powalowski (tpowa) - Wednesday, 13 August 2014, 18:07 GMT
|
Details
Description:
System does not boot properly, in detail the system seems to boot more or less successfully but the screen/display is not usable. In fact it displays something that looks like a persian carpet. After some seconds, the screen goes black. Switching TTYs does not have an effect (Ctrl+Alt+F{1,2,3,...}) on the display. Behind, the system is still responsive, like pressing Ctrl+Alt+Delete followed by Enter does trigger a reboot/poweroff (in my case, this seems to trigger the KDM functions on the login screen). Additional info: Packages installed which seem to be problematic: linux-3.15.1-1-x86_64 intel-dri-10.1.1-2-x86_64 mesa-10.2.1-2-x86_64 mesa-libgl-10.2.1-2-x86_64 After a downgrade to my previous setup linux-3.14.4-1-x86_64 intel-dri-10.1.4-1-x86_64 mesa-10.1.4-1-x86_64 mesa-libgl-10.1.4-1-x86_64 the problem does not occur anymore. Switching back to linux-3.15.1-1-x86_64 causes the same problem again. Stacktrace in journal: Jun 19 20:22:25 chandra kernel: ------------[ cut here ]------------ Jun 19 20:22:25 chandra kernel: WARNING: CPU: 1 PID: 29 at drivers/gpu/drm/i915/intel_display.c:931 assert_pll+0x6f/0x80 [i915]() Jun 19 20:22:25 chandra kernel: PLL state assertion failure (expected on, current off) Jun 19 20:22:25 chandra kernel: Modules linked in: joydev mousedev hid_generic usbhid hid iTCO_wdt iTCO_vendor_support dell_wmi sparse_keymap snd_hda_codec_realtek i915 snd_hda_codec_generic kvm_intel snd_hda_intel kvm snd_hda_controller uas dell_laptop uvcvideo drm_kms_helper rfkill snd_hda_codec videobuf2_vmalloc videobuf2_memops dcdbas videobuf2_core microcode usb_storage drm snd_hwdep videodev media psmouse evdev mac_hid serio_raw i2c_i801 snd_pcm snd_timer r8169 lpc_ich ssb mii snd pcmcia pcmcia_core soundcore shpchp i2c_algo_bit wmi tpm_infineon tpm_tis tpm battery ac i2c_core intel_agp intel_gtt video button acpi_cpufreq processor ext4 crc16 mbcache jbd2 sd_mod crc_t10dif crct10dif_common sr_mod cdrom ata_generic pata_acpi atkbd libps2 sdhci_pci sdhci led_class ahci libahci mmc_core firewire_ohci ata_piix libata Jun 19 20:22:25 chandra kernel: scsi_mod firewire_core crc_itu_t i8042 serio ehci_pci uhci_hcd ehci_hcd usbcore usb_common [last unloaded: hwmon] Jun 19 20:22:25 chandra kernel: CPU: 1 PID: 29 Comm: kworker/1:1 Tainted: G W 3.15.1-1-ARCH #1 Jun 19 20:22:25 chandra kernel: Hardware name: Dell Inc. Vostro1310/0H528C, BIOS A10 07/10/2008 Jun 19 20:22:25 chandra kernel: Workqueue: events console_callback Jun 19 20:22:25 chandra kernel: 0000000000000000 00000000968504ab ffff8800ba5bfb08 ffffffff81507c61 Jun 19 20:22:25 chandra kernel: ffff8800ba5bfb50 ffff8800ba5bfb40 ffffffff81069acd 0000000000000001 Jun 19 20:22:25 chandra kernel: ffff8800b956c000 000000000000a800 0000000000000001 ffff8800b9a06000 Jun 19 20:22:25 chandra kernel: Call Trace: Jun 19 20:22:25 chandra kernel: [<ffffffff81507c61>] dump_stack+0x4d/0x6f Jun 19 20:22:25 chandra kernel: [<ffffffff81069acd>] warn_slowpath_common+0x7d/0xa0 Jun 19 20:22:25 chandra kernel: [<ffffffff81069b4c>] warn_slowpath_fmt+0x5c/0x80 Jun 19 20:22:25 chandra kernel: [<ffffffffa064475b>] ? gen4_read32+0x4b/0xd0 [i915] Jun 19 20:22:25 chandra kernel: [<ffffffffa065347f>] assert_pll+0x6f/0x80 [i915] Jun 19 20:22:25 chandra kernel: [<ffffffffa0658de1>] intel_crtc_load_lut+0x1d1/0x1f0 [i915] Jun 19 20:22:25 chandra kernel: [<ffffffffa045249e>] drm_fb_helper_setcmap+0x38e/0x480 [drm_kms_helper] Jun 19 20:22:25 chandra kernel: [<ffffffff812f41a7>] ? fbcon_switch+0x3c7/0x5e0 Jun 19 20:22:25 chandra kernel: [<ffffffff8130178c>] fb_set_cmap+0x6c/0x150 Jun 19 20:22:25 chandra kernel: [<ffffffff812f08dc>] fbcon_set_palette+0x14c/0x180 Jun 19 20:22:25 chandra kernel: [<ffffffff8136a2e0>] set_palette+0x40/0x60 Jun 19 20:22:25 chandra kernel: [<ffffffff8136aae4>] redraw_screen+0x1b4/0x250 Jun 19 20:22:25 chandra kernel: [<ffffffff813612ef>] complete_change_console+0x3f/0xe0 Jun 19 20:22:25 chandra kernel: [<ffffffff81362ca9>] change_console+0x59/0xa0 Jun 19 20:22:25 chandra kernel: [<ffffffff8136cbd4>] console_callback+0x114/0x190 Jun 19 20:22:25 chandra kernel: [<ffffffff81085b8d>] ? pwq_dec_nr_in_flight+0x4d/0xb0 Jun 19 20:22:25 chandra kernel: [<ffffffff81086178>] process_one_work+0x168/0x450 Jun 19 20:22:25 chandra kernel: [<ffffffff81086bd2>] worker_thread+0x132/0x3e0 Jun 19 20:22:25 chandra kernel: [<ffffffff81086aa0>] ? manage_workers.isra.23+0x2d0/0x2d0 Jun 19 20:22:25 chandra kernel: [<ffffffff8108d3ca>] kthread+0xea/0x100 Jun 19 20:22:25 chandra kernel: [<ffffffff8108d2e0>] ? kthread_create_on_node+0x1a0/0x1a0 Jun 19 20:22:25 chandra kernel: [<ffffffff815158fc>] ret_from_fork+0x7c/0xb0 Jun 19 20:22:25 chandra kernel: [<ffffffff8108d2e0>] ? kthread_create_on_node+0x1a0/0x1a0 Jun 19 20:22:25 chandra kernel: ---[ end trace fe5e2d75762300b4 ]--- lspci: 00:00.0 Host bridge: Intel Corporation Mobile PM965/GM965/GL960 Memory Controller Hub (rev 0c) 00:02.0 VGA compatible controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (primary) (rev 0c) 00:02.1 Display controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (secondary) (rev 0c) 00:1a.0 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #4 (rev 03) 00:1a.1 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #5 (rev 03) 00:1a.7 USB controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #2 (rev 03) 00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 03) 00:1c.0 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 1 (rev 03) 00:1c.1 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 2 (rev 03) 00:1c.3 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 4 (rev 03) 00:1c.4 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 5 (rev 03) 00:1d.0 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #1 (rev 03) 00:1d.1 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #2 (rev 03) 00:1d.2 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #3 (rev 03) 00:1d.7 USB controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #1 (rev 03) 00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev f3) 00:1f.0 ISA bridge: Intel Corporation 82801HM (ICH8M) LPC Interface Controller (rev 03) 00:1f.1 IDE interface: Intel Corporation 82801HM/HEM (ICH8M/ICH8M-E) IDE Controller (rev 03) 00:1f.2 SATA controller: Intel Corporation 82801HM/HEM (ICH8M/ICH8M-E) SATA Controller [AHCI mode] (rev 03) 00:1f.3 SMBus: Intel Corporation 82801H (ICH8 Family) SMBus Controller (rev 03) 06:00.0 Network controller: Broadcom Corporation BCM4312 802.11b/g LP-PHY (rev 01) 07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 02) 08:05.0 FireWire (IEEE 1394): O2 Micro, Inc. Firewire (IEEE 1394) (rev 02) 08:05.2 SD Host controller: O2 Micro, Inc. Integrated MMC/SD Controller (rev 02) 08:05.3 Mass storage controller: O2 Micro, Inc. Integrated MS/xD Controller (rev 01) lspci -nnvv: 00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (primary) [8086:2a02] (rev 0c) (prog-if 00 [VGA controller]) Subsystem: Dell Device [1028:026f] Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+ Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 0 Interrupt: pin A routed to IRQ 44 Region 0: Memory at f8000000 (64-bit, non-prefetchable) [size=1M] Region 2: Memory at d0000000 (64-bit, prefetchable) [size=256M] Region 4: I/O ports at 1800 [size=8] Expansion ROM at <unassigned> [disabled] Capabilities: <access denied> Kernel driver in use: i915 Kernel modules: i915 Steps to reproduce: Boot a system with the above mentioned configuration. My hardware is a Dell Vostro 1310. Please ask for more details if required. Thanks. |
This task depends upon
Packages installed which seem to be problematic:
linux-3.15.1-1-x86_64
intel-dri-10.2.1-2-x86_64 <-- 10.1 vs. 10.2
mesa-10.2.1-2-x86_64
mesa-libgl-10.2.1-2-x86_64
The specific versions of the packages I have installed are:
linux 3.14.6-1
intel-dri 10.2.1-2
mesa 10.2.1-2
mesa-libgl 10.2.1-2
I can even log in before the machine freezes. During boot I get some strange colors on the screen. I have a HP Zbook 15 with NVIDIA Optimus graphics.
I attach boot messages (output from journalctl).
Update: Everything works fine with 3.15.2 and computer only (just strange colors during boot still appear). However, when the computer is docked, with external monitor connected, I still get kernel panic about 20 seconds after boot is completed.
It isn't working even after downgrade linux, intel-dri, mesa, mesa-libgl
I believe the culprit has been bisected:
https://bugs.freedesktop.org/show_bug.cgi?id=80010
Upgrading back to 3.15.1-1 brings back the problem. The problem in my case is that upon boot, but before login, the display suddenly
shows some artifacts for a few seconds, then goes blank. The system underneath seems to be responsive. The artifacts look like this:
http://postimg.org/image/6zc8c7hk9/
The problem persists even without a login manager or any kind of automatic login.
Some interesting information: With the problematic 3.15.1-1 kernel, If I plug an external VGA monitor before powering on,
then the computer will boot as usual! Even if I unplug the VGA monitor after the boot, the computer screen works normally.
I found if I blacklist i915 module, I can get to a usuable login-promt (Or, init=/usr/bin/bash in kernal.) It seems to die at : "[ 9.486218] fb: switching to inteldrmfb from VESA VGA
[ 9.751832] fbcon: inteldrmfb (fb0) is primary device
[ 10.266934] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device"
If it is blacklisted, when your try to run Xorg: "[ 178.468] (EE) intel(0): Detected a hung GPU, disabling acceleration.
[ 178.468] removing GPU device /sys/devices/pci0000:00/0000:00:02.0/drm/card0 /dev/dri/card0
[ 178.468] (II) config/udev: Adding drm device (/dev/dri/card0)
[ 178.468] (II) xfree86: Adding drm device (/dev/dri/card0)
[ 178.468] setversion 1.4 failed: Permission denied
[ 178.468] removing GPU device /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1 (null)
[ 178.468] removing GPU device /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-VGA-1 (null)
[ 178.468] removing GPU device /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-DVI-D-1 (null)
"
I downgraded to linux 3.14.6-1 and it works properly again.
Never tryed unblacklisted xorg, I can if someone really wants me to though.
Not sure if that is an issue, but just in case.
This is a Lenovo ThinkPad T500.
$ lspci -nnvv | grep -i graphics
00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07) (prog-if 00 [VGA controller])
00:02.1 Display controller [0380]: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a43] (rev 07)
Downgrading from linux-3.15-1 to linux-3.14.6-1 fixes the issue.
[1] https://bugs.freedesktop.org/show_bug.cgi?id=80151
Kernels which I tested 3.15.3-1, 3.15.1-1 --> these dont boot. Downgrading to linux-lts or 3.14.6-1 boots fine without any errors.
i686 HP-Pavilion. Logs from journal, lspci -nvv and lspci are attached.
I was able to reproduce this a couple of times by using 3.15.x kernels.
Please let me know if any other information is required.
EDIT: I just tested booting with linux-3.15.4[testing]. Unfortunately it didnt work. I got the same screen i got last time. Journal from this boot is attached.
[1] https://bugs.freedesktop.org/show_bug.cgi?id=76276#c41
[2] http://marc.info/?l=linux-stable-commits&m=140009793220259
[3] https://bugs.freedesktop.org/show_bug.cgi?id=80151
http://cgit.freedesktop.org/drm-intel/commit/?id=7465139a3eb405d4f0b9c75063d189ffc52a617b
Same problem here, hardware is Vostro1510, but if I plug VGA cable to external monitor, the boot proceeds normally.
Attached, my journalctl.
@bidulock Please don't hijack this bug report about intel GPUs. Open a new bug if you must, but I recommend you research the radeon-drm mailing lists and bugzilla at freedesktop.org[1][2] and take your issue upstream.
[1]<http://dri.freedesktop.org/wiki/Radeon/>
[2] <http://bugzilla.freedesktop.org/>
Thank you.
EDIT: I attached journal log with 3.15.5 [i686, testing]
journal_3.15.5.txt (0 KiB)
Hardware:
# lspci
00:00.0 Host bridge: Intel Corporation Mobile 915GM/PM/GMS/910GML Express Processor to DRAM Controller (rev 03)
00:02.0 VGA compatible controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
It fails for both:
linux-3.15.5-1-i686
linux-lts-3.14.12-1-i686
Had to fallback to:
linux-lts-3.10.46-1-i686
@Anurag, your problem is mysteriuos but your laptop is a frakenmonster of ich7 and ich8 components (my laptop has the same core components but it is a full ich8 platform). If you read you journal you'll find this:
Jul 10 13:20:25 TF-hp-arch kernel: [drm] GPU HANG: ecode -1:0x00000000, reason: Command parser error, iir 0x00008000, action: continue
Jul 10 13:20:25 TF-hp-arch kernel: [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.
Jul 10 13:20:25 TF-hp-arch kernel: [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel
Jul 10 13:20:25 TF-hp-arch kernel: [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue.
Jul 10 13:20:25 TF-hp-arch kernel: [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it.
Jul 10 13:20:25 TF-hp-arch kernel: [drm] GPU crash dump saved to /sys/class/drm/card0/error
I suggest you file a bug upstream.
VGA compatible controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (primary) (rev 0c) (prog-if 00 [VGA controller])
dmesg shows:
[ 17.350064] [drm] stuck on render ring
[ 17.350891] [drm] GPU HANG: ecode 0:0x0fe505ae, in X [497], reason: Ring hung, action: reset
[ 17.350901] i915: render error detected, EIR: 0x00000010
[ 17.350906] i915: page table error
[ 17.350908] i915: PGTBL_ER: 0x00000101
[ 17.350942] [drm:intel_pipe_set_base] *ERROR* pin & fence failed
[ 17.856759] [drm:i915_reset] *ERROR* Failed to reset chip: -110
Blank screen; text console login.
00:02.1 Display controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (secondary) (rev 0c)
[2014-07-20 13:00] [PACMAN] upgraded mesa (10.2.3-2 -> 10.2.4-1)
[2014-07-20 13:00] [PACMAN] upgraded mesa-libgl (10.2.3-2 -> 10.2.4-1)
[2014-07-20 13:00] [PACMAN] upgraded intel-dri (10.2.3-2 -> 10.2.4-1)
[2014-07-20 13:00] [PACMAN] upgraded libxi (1.7.3-1 -> 1.7.4-1)
[2014-07-20 13:00] [PACMAN] upgraded linux (3.15.5-1 -> 3.15.5-2)
[2014-07-20 13:01] [PACMAN] upgraded linux-lts (3.14.12-1 -> 3.14.13-1)
journalctl and dmesg clean
Thank you!
core/linux-3.15.7-1-i686
Note the arch: i686.
Blank screen; text console login.
00:02.1 Display controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
jb, I found that the xinit update to 1.6 caused a big mess of X not starting. If you get a console login, that's farther than I ever got when broken.
I do not utilize GUI login; configured for text login, but do not get it on the screen.
I did some testing. I enabled GUI login.
I run 3.15.7-1-i686 (and 3.15.8-1-i686 later) kernel and it works, with some twist:
- on first attempt, I got display manager but the brightness was low, the desktop was of low brightness too.
Hitting Fn+F9 (brightness lower) the brightness was restored. Logged out the desktop, back to display manager, and
all was OK.
- on subsequent boots to GUI (display manager) there was not problem with brightness any more.
I did some more testing - I enabled non-GUI login.
On boot, the screen went blank while starting various services and stayed so. I hit Fn+F9 (brightness lower) and
the brightness was restored, and the login text became visible as expected.
Note: any attempts to restore the screen with other keys or switching tty's back and forth with Alt+Fx failed.
The problem occcurs in desktop env as well - after suspend/resume the brightness has to be restored with Fn+F9
(brightness lower).
As I already mentioned, this does not happen with older kernels (I used as fallback linux-lts-3.10.46-1-i686),
so there is a fix needed for this.
Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (primary) (rev 03)
Looked fixed.
Screen is working now.
I tested some kernels (ARCH, lts, ck, zen) only lts works.
looking dmesg I've found two added lines for not working setup:
Reserving Intel graphics stolen memory at 0xbf800000-0xbfffffff
[drm:i965_irq_handler] *ERROR* pipe A underrun
after switching from console and Xorg the system also dumps:
drm:intel_pipe_config_compare ERROR mismatch in dpll_hw_state.dpll
I'm attaching two dmesg outputs (error/ok) to have a diff..
Hope this helps,
Andrea
dmesg.ok (55.8 KiB)
Only happens with linux-3.16.0-2 from testing. Downgrading to linux 3.15.8-1 and all is working back.
My lscpi :
00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) (prog-if 00 [VGA controller])
Subsystem: Toshiba America Info Systems Device ff67
Flags: bus master, fast devsel, latency 0, IRQ 46
Memory at d0000000 (64-bit, non-prefetchable) [size=4M]
Memory at c0000000 (64-bit, prefetchable) [size=256M]
I/O ports at 5110 [size=8]
Expansion ROM at <unassigned> [disabled]
Capabilities: <access denied>
Kernel driver in use: i915
Kernel modules: i915
00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07) (prog-if 00 [VGA controller])
Subsystem: Lenovo Device [17aa:20e4]
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 0
Interrupt: pin A routed to IRQ 49
Region 0: Memory at f2000000 (64-bit, non-prefetchable) [size=4M]
Region 2: Memory at d0000000 (64-bit, prefetchable) [size=256M]
Region 4: I/O ports at 1800 [size=8]
Expansion ROM at <unassigned> [disabled]
Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
Address: fee0300c Data: 4192
Capabilities: [d0] Power Management version 3
Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
Kernel driver in use: i915
Kernel modules: i915
My lscpi :
00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) (prog-if 00 [VGA controller])
Subsystem: Toshiba America Info Systems Device ff67
Flags: bus master, fast devsel, latency 0, IRQ 46
Memory at d0000000 (64-bit, non-prefetchable) [size=4M]
Memory at c0000000 (64-bit, prefetchable) [size=256M]
I/O ports at 5110 [size=8]
Expansion ROM at <unassigned> [disabled]
Capabilities: <access denied>
Kernel driver in use: i915
Kernel modules: i915
Just upgraded to 3.16-0-2-ARCH and IT WORKS LIKE A CHARM !!
I can switch from console to Xorg and it does not hang to black screen anymore.
Great news for my little old laptop..
Thanks thread,
Andrea
P.S. this is an answer for @vorbote.
With any of the kernel before 3.16 I had a problem ob black screen randomly appearing, It seemed the system could only render one of the Xorg or TTY and was unable to switch between the two.
I've checked also without login manager but the problem was the same.
One observation and question @andrea, are you trying to switch VTs from the GDM login screen before creating a user session? If so, you may be hitting a bug in GDM interacting with systemd-logind instead where, as far as I have observed, it won't relinquish TTY ownership correctly if it is running the only seat in the system. As soon as you have a second seat, namely your session, VT switching works normally. As far as I can tell this seems fixed in the development version of GNOME 3.14 at least in the Fedora 21 instance I have in the external disk.
Those with issues please open a new bug report.