X will not start on a Thinkpad 240 using neomagic

Michel Dänzer michel at daenzer.net
Wed Jan 24 16:08:14 UTC 2018

On 2018-01-24 04:55 PM, Adam Jackson wrote:
> On Wed, 2018-01-24 at 01:12 +0000, Alex Bowden wrote:
>> I have a Thinkpad 240 with a Neomagic NM2160 and I keep having an issue
>> with the neomagic driver. I think I have narrowed it down to the kernel
>> refusing to mmap the framebuffer. I created a program called testneo.c
>> to attempt to use pci_device_map_range to access the framebuffer but
>> it always returns 22 (Invalid argument).
> I'm not sure why that would fail, but...

It could be related to the Linux kernel's CONFIG_IO_STRICT_DEVMEM,
excerpt from the corresponding help text:

          If this option is switched on, the /dev/mem file only allows
          userspace access to *idle* io-memory ranges (see /proc/iomem) This
          may break traditional users of /dev/mem (dosemu, legacy X, etc...)
          if the driver using a given range cannot be disabled.

Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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