# # Amateur Radio protocols and AX.25 device configuration # menuconfig HAMRADIO depends on NET && !S390 bool "Amateur Radio support" help If you want to connect your Linux box to an amateur radio, answer Y here. You want to read and more specifically about AX.25 on Linux . Note that the answer to this question won't directly affect the kernel: saying N will just cause the configurator to skip all the questions about amateur radio. comment "Packet Radio protocols" depends on HAMRADIO config AX25 tristate "Amateur Radio AX.25 Level 2 protocol" depends on HAMRADIO help This is the protocol used for computer communication over amateur radio. It is either used by itself for point-to-point links, or to carry other protocols such as tcp/ip. To use it, you need a device that connects your Linux box to your amateur radio. You can either use a low speed TNC (a Terminal Node Controller acts as a kind of modem connecting your computer's serial port to your radio's microphone input and speaker output) supporting the KISS protocol or one of the various SCC cards that are supported by the generic Z8530 or the DMA SCC driver. Another option are the Baycom modem serial and parallel port hacks or the sound card modem (supported by their own drivers). If you say Y here, you also have to say Y to one of those drivers. Information about where to get supporting software for Linux amateur radio as well as information about how to configure an AX.25 port is contained in the AX25-HOWTO, available from . You might also want to check out the file in the kernel source. More information about digital amateur radio in general is on the WWW at . To compile this driver as a module, choose M here: the module will be called ax25. config AX25_DAMA_SLAVE bool "AX.25 DAMA Slave support" default y depends on AX25 help DAMA is a mechanism to prevent collisions when doing AX.25 networking. A DAMA server (called "master") accepts incoming traffic from clients (called "slaves") and redistributes it to other slaves. If you say Y here, your Linux box will act as a DAMA slave; this is transparent in that you don't have to do any special DAMA configuration. Linux cannot yet act as a DAMA server. This option only compiles DAMA slave support into the kernel. It still needs to be enabled at runtime. For more about DAMA see . If unsure, say Y. # placeholder until implemented config AX25_DAMA_MASTER bool 'AX.25 DAMA Master support' depends on AX25_DAMA_SLAVE && BROKEN help DAMA is a mechanism to prevent collisions when doing AX.25 networking. A DAMA server (called "master") accepts incoming traffic from clients (called "slaves") and redistributes it to other slaves. If you say Y here, your Linux box will act as a DAMA master; this is transparent in that you don't have to do any special DAMA configuration. Linux cannot yet act as a DAMA server. This option only compiles DAMA slave support into the kernel. It still needs to be explicitly enabled, so if unsure, say Y. config NETROM tristate "Amateur Radio NET/ROM protocol" depends on AX25 help NET/ROM is a network layer protocol on top of AX.25 useful for routing. A comprehensive listing of all the software for Linux amateur radio users as well as information about how to configure an AX.25 port is contained in the Linux Ham Wiki, available from . You also might want to check out the file . More information about digital amateur radio in general is on the WWW at . To compile this driver as a module, choose M here: the module will be called netrom. config ROSE tristate "Amateur Radio X.25 PLP (Rose)" depends on AX25 help The Packet Layer Protocol (PLP) is a way to route packets over X.25 connections in general and amateur radio AX.25 connections in particular, essentially an alternative to NET/ROM. A comprehensive listing of all the software for Linux amateur radio users as well as information about how to configure an AX.25 port is contained in the Linux Ham Wiki, available from . You also might want to check out the file . More information about digital amateur radio in general is on the WWW at . To compile this driver as a module, choose M here: the module will be called rose. menu "AX.25 network device drivers" depends on HAMRADIO && AX25 source "drivers/net/hamradio/Kconfig" endmenu
authorLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
commit39cb2c9a316e77f6dfba96c543e55b6672d5a37e (patch)
tree98fe974ee4e20121253de7f61fc8d01bdb3821c1 /net/sched/act_pedit.c
parent2c5d9555d6d937966d79d4c6529a5f7b9206e405 (diff)
drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()
I've seen this trigger twice now, where the i915_gem_object_to_ggtt() call in intel_unpin_fb_obj() returns NULL, resulting in an oops immediately afterwards as the (inlined) call to i915_vma_unpin_fence() tries to dereference it. It seems to be some race condition where the object is going away at shutdown time, since both times happened when shutting down the X server. The call chains were different: - VT ioctl(KDSETMODE, KD_TEXT): intel_cleanup_plane_fb+0x5b/0xa0 [i915] drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper] intel_atomic_commit_tail+0x749/0xfe0 [i915] intel_atomic_commit+0x3cb/0x4f0 [i915] drm_atomic_commit+0x4b/0x50 [drm] restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper] drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper] drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper] intel_fbdev_set_par+0x18/0x70 [i915] fb_set_var+0x236/0x460 fbcon_blank+0x30f/0x350 do_unblank_screen+0xd2/0x1a0 vt_ioctl+0x507/0x12a0 tty_ioctl+0x355/0xc30 do_vfs_ioctl+0xa3/0x5e0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x13/0x94 - i915 unpin_work workqueue: intel_unpin_work_fn+0x58/0x140 [i915] process_one_work+0x1f1/0x480 worker_thread+0x48/0x4d0 kthread+0x101/0x140 and this patch purely papers over the issue by adding a NULL pointer check and a WARN_ON_ONCE() to avoid the oops that would then generally make the machine unresponsive. Other callers of i915_gem_object_to_ggtt() seem to also check for the returned pointer being NULL and warn about it, so this clearly has happened before in other places. [ Reported it originally to the i915 developers on Jan 8, applying the ugly workaround on my own now after triggering the problem for the second time with no feedback. This is likely to be the same bug reported as https://bugs.freedesktop.org/show_bug.cgi?id=98829 https://bugs.freedesktop.org/show_bug.cgi?id=99134 which has a patch for the underlying problem, but it hasn't gotten to me, so I'm applying the workaround. ] Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net/sched/act_pedit.c')