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Message #161327
[Bug 1534647] Re: Collateral damage due to kernel configuration change enabling CONFIG_ZONE_DEVICE (Kernel 4.4 amd64)
Niels - restoring ZONE_DMA in generic should have reinstated the build
for snd-ice1712. I've a test build of 4.4.0-6.21 (currently building in
Launchpad) that shows this module in both lowlatency and generic. Lets
wait and see how 4.4.0-6.21 turns out.
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https://bugs.launchpad.net/bugs/1534647
Title:
Collateral damage due to kernel configuration change enabling
CONFIG_ZONE_DEVICE (Kernel 4.4 amd64)
Status in linux package in Ubuntu:
Fix Committed
Status in mudita24 package in Ubuntu:
Confirmed
Status in linux source package in Xenial:
Fix Committed
Status in mudita24 source package in Xenial:
Confirmed
Bug description:
Late in the kernel 4.4 RC (Release Candidate) cycle (between rc7 and
rc8), Ubuntu implemented an amd64 kernel configuration change enabling
CONFIG_ZONE_DEVICE.
The related email: https://lists.ubuntu.com/archives/kernel-
team/2016-January/067683.html
The commit message does mention collateral damage: "In effect, this precludes devices that can only DMA from memory addresses below 16MB".
Indeed we already have a complaint about a sound card that doesn't work as of kernel 4.4-rc8.
If CONFIG_ZONE_DEVICE is enabled, then CONFIG_ZONE_DMA is forced to disabled, which in turn forces these devices, all are sound cards, and their derivative devices, to be disabled:
Avance Logic ALS300/ALS300+
ALi M5451 PCI Audio Controller
Aztech AZF3328 / PCI168
Emu10k1 (SB Live!, Audigy, E-mu APS)
Emu10k1X (Dell OEM Version)
ESS ES1938/1946/1969 (Solo-1)
ESS ES1968/1978 (Maestro-1/2/2E)
ICEnsemble ICE1712 (Envy24)
ESS Allegro/Maestro3
S3 SonicVibes
Trident 4D-Wave DX/NX; SiS 7018.
References: linux/mm/Kconfig; linux/sound/pci/Kconfig
One test done (suggested by apw on IRC) was to remove the dependency of ZONE_DEVICE on !ZONE_DMA, but that causes:
"#error ZONES_SHIFT -- too many zones configured adjust calculation", as apw predicted.
In a mindless way, I tried to allow more zones in linux/include/linux/page-flags-layout.h, but that caused a bunch of "shifting by too many bits type errors. Anyway it seems that MAX_NR_ZONES is, at least partially, hard coded to 4 in some array definitions and such.
Please do not ask me to do "apport-collect" for this bug report as it
is not needed, nor relevant.
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References