bugGNU GRUB - Bugs: bug #50931, Page Fault Exception when grub...


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bug #50931: Page Fault Exception when grub loads with an Nvidia cards

Submitted by:  Nathan Zimmer <nzimmer>
Submitted on:  Wed 03 May 2017 04:32:30 PM UTC  
Category: BootingSeverity: Major
Priority: 5 - NormalItem Group: Software Error
Status: NonePrivacy: Public
Assigned to: NoneOriginator Name: Nathan Zimmer
Open/Closed: OpenRelease: 
Release: Git masterReproducibility: Every Time
Planned Release: None

Tue 16 May 2017 07:21:28 PM UTC, comment #3:

I tried it on all 3 of the boxes I knew had the error and it seemed to fix them all.

Nathan Zimmer <nzimmer>
Mon 08 May 2017 05:13:58 PM UTC, comment #2:

That did it on my one test box. I'll see if I can find any more test boxes around but ... right now it looks good to me.

Nathan Zimmer <nzimmer>
Sat 06 May 2017 06:10:57 AM UTC, comment #1:

Does attached patch help?

(file #40605)

Andrei Borzenkov <arvidjaar>
Project Member
Wed 03 May 2017 04:32:30 PM UTC, original submission:

On some of our uv systems with nvidia card grub takes a Page Fault Exception.

After some digging it was discovered that the efi_uga module is not able to handle a framebuffer at a 64-bit address.

In find_card (grub_pci_device_t dev, grub_pci_id_t pciid, void *data) the 64-bit VMEM bar in base64 is correctly calculated.

The problem is that *ctx->fb_base is type grub_uint32_t, but base64 is type grub_uint64_t. So grub is storing a
64-bit framebuffer pointer into a 32-bit field, truncating off the
high bits, and leaving zeros.
This size mismatch goes all the way back up the call chain:

Nathan Zimmer <nzimmer>


Attached Files
file #40605:  uga-64bit-fb.patch added by arvidjaar (3KiB - text/x-patch)


Depends on the following items: None found

Items that depend on this one: None found


Carbon-Copy List
  • -unavailable- added by arvidjaar (Updated the item)
  • -unavailable- added by nzimmer (Submitted the item)

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    Follows 1 latest change.

    Date Changed By Updated Field Previous Value => Replaced By
    Sat 06 May 2017 06:10:57 AM UTCarvidjaarAttached File-=>Added uga-64bit-fb.patch, #40605

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