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Bug 967265 - Grub2 does not ship with iorw module, which prevents booting on certain hardware
Grub2 does not ship with iorw module, which prevents booting on certain hardware
Product: Fedora
Classification: Fedora
Component: grub2 (Show other bugs)
Unspecified Unspecified
unspecified Severity medium
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Assigned To: Peter Jones
Fedora Extras Quality Assurance
: Reopened
Depends On:
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Reported: 2013-05-26 02:53 EDT by William Brown
Modified: 2016-12-20 07:38 EST (History)
5 users (show)

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Last Closed: 2016-12-20 07:38:51 EST
Type: Bug
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RHEL 7.3 requirements from Atomic Host:
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Description William Brown 2013-05-26 02:53:24 EDT
Description of problem:
Certain laptops, especially Apple MacBook pro's ship with a graphics multiplexer due to their dual graphics nature. At this time, this support is still broken in the kernel and will not be fixed soon.

In order to boot these laptops the command "outb" must be available in grub2 so that the gmux can be put into a sane state so the machine will boot.

In order for this to happen, the iorw module should be built by default in grub2. This will not affect any other hardware configurations, but will simplify the currently complex situation for Apple Mac hardware.

It grub2.spec line 538 add:


To the GRUB_MODULES section.
Comment 1 Mads Kiilerich 2013-05-27 19:56:55 EDT
Can you give any references that indicate that this really is the best solution to a real problem?

Even then: This will be of very limited use without a mechanism for using it automatically from grub.cfg.

If you have to generate a custom grub.cfg for this anyway then you can just as well run grub2-install as upstream intended and create a custom .efi .
Comment 2 William Brown 2013-05-31 01:11:11 EDT

At this time, when an intel MBP boots, both GPU's are powered on. You can run the high powered gpu, without (much) issue at this point.

Swapping to the intel gpu however, causes the display to go blank. All my attempts to convince kernel developers to actually help, have fallen on deaf ears.

To avoid this, the only solution is to before booting, swap the graphics card to the low powered GPU before boot. To achieve this you must probe memory values to achieve this.

However, you make a good point. I still need to make a custom configuration to grub. Thus I will close this issue.
Comment 3 Mads Kiilerich 2013-06-02 18:29:58 EDT
A howto, for example linked from "common bugs" would probably be helpful for someone ;-)
Comment 4 William Brown 2013-06-02 21:21:04 EDT
A fix from the kernel developers should be the only solution. However, they seem to "not care" about this issue ;)

I will write a page on the Fedora wiki later when I have time about this issue.
Comment 5 Lubos Kocman 2016-02-18 16:44:32 EST
Re-opening ... since this is still an issue in f23.

Comment 6 Fedora End Of Life 2016-11-24 05:58:59 EST
This message is a reminder that Fedora 23 is nearing its end of life.
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Comment 7 Fedora End Of Life 2016-12-20 07:38:51 EST
Fedora 23 changed to end-of-life (EOL) status on 2016-12-20. Fedora 23 is
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