Messages in this thread | | | From | Randy Wright <> | Subject | Re: [PATCH RFC] function probe_roms accessing improper addresses | Date | Tue, 23 Oct 2012 10:05:01 -0600 (MDT) |
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Hi Matthew,
You made some interesting suggestions:
> 1) Declare that any x86 hardware supported by Linux *must* support > probing in this address region
On the first: one way to be compliant with such a requirement would be to design systems that implement softfail in this particular region. What about a system that hardfails, but on which the resulting machine check can be handled by the kernel machine check handler? Would appropriate re-ordering of the kernel initialization code to support such systems be acceptable?
Also, let me mention a possible amendment to your first idea: what if the mandate that probing be supported were qualified by some attribute that could be indicated in the UEFI environment? For example: instead of just a hole in the UEFI memory map, what if this range was specifically present and typed as EfiUnusableMemory? Another idea for UEFI systems - but one requiring a UEFI specification change - might be adding a UEFI variable that if present, indicates any area not explicitly included and typed in the UEFI memory map (including the legacy adapter region) must be explicitly avoided by an OS.
> 2) Don't call probe_roms() by default, but leave it up to the graphics > drivers. If they can get the rom by any other means then don't call it.
One the second idea: there are a quite a lot of video drivers in the kernel source tree. Do you have a suggestion for how to evaluate which ones rely on the setup performed by probe_roms?
-- Randy Wright Hewlett-Packard Company Phone: (970) 898-0998 Mail: rwright@hp.com
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