For quite some time, I haven’t been able to use wireless communication on my HP EliteBook 8530w. All wireless communications (wifi, wwan, bluetooth) are listed as Hard Blocked by rfkill.
It appears, a kernel bug was introduces with Linux 3.13. This bug is in the hp-wmi kernel module, which controls the hardware buttons, including the wireless switch
My current kernel is 4.3.3, so,we obtain the source file for the hp-wmi for this kernel : https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/plain/drivers/platform/x86/hp-wmi.c?id=refs/tags/v4.3.3
We obtain the patch file https://bugzilla.kernel.org/attachment.cgi?id=122901
We apply the patch to the file
patch -p 4 < hp_wmi.patch
We put a Makefile with this file in it
obj-$(CONFIG_HP_WMI) += hp-wmi.o
And we comile it
make -C /lib/modules/`uname -r`/build M=$PWD
Backup the original kernel module
mv /usr/lib/modules/`uname -r`/kernel/drivers/platform/x86/hp-wmi.ko.gz /usr/lib/modules/`uname -r`/kernel/drivers/platform/x86/hp-wmi.ko.gz.bak
And put the patched version in its place.
mv ./hp-wmi.ko.gz /usr/lib/modules/`uname -r`/kernel/drivers/platform/x86/hp-wmi.ko.gz
When we press the wireless button now, rfkill reports
Hard Blocked: no and we're able to use WiFi, Bluetooth and 3G again.