[bug #47711] EFI boot hang when driver allocates more than 1.5GB RAM above 4GB

[B Cran]

URL:
  <http://savannah.gnu.org/bugs/?47711>

                 Summary: EFI boot hang when driver allocates more than 1.5GB
RAM above 4GB
                 Project: GNU GRUB
            Submitted by: bcran
            Submitted on: Fri 15 Apr 2016 09:06:32 PM GMT
                Category: Booting
                Severity: Major
                Priority: 5 - Normal
              Item Group: Software Error
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: B Cran
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 
                 Release: Git master
         Reproducibility: Every Time
         Planned Release: None

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Details:

I have a UEFI driver that, when sufficient memory is available, uses lots of
it for its work, for example routinely allocating 3-4GB.  In an attempt to
avoid problems with other drivers, applications or bootloaders, allocations
start from the top of RAM and work towards the bottom. 

GRUB master (abf9beb7d667d3604774753cf698c439c6fbc736) hangs sometime after
calling `b->grub_efi_finish_boot_services` in grub_linux_boot()
(grub-core/loader/i386/linux.c) when the following EFI code is run in a
driver:

```
  EFI_PHYSICAL_ADDRESS addr = 0x180000000;
  EFI_STATUS status = gBS->AllocatePages(AllocateAddress, EfiBootServicesData,
0x80000, &addr);
```

For simplicity of replicating the problem this doesn't figure out where the
top of memory is, but instead just chooses to allocate at 6GB.

I'm running OVMF from edk2 master under qemu 2.5.50 with:

qemu-system-x86_64 -name uefi -M pc -m size=20G -cpu host -drive
unit=0,if=pflash,format=raw,file=OVMF.fd -nodefaults -realtime mlock=off
-enable-kvm -S -s -rtc base=utc -monitor stdio -drive
file=uefi3.img,if=ide,media=disk,format=raw -vga std -vnc :0 -device
vfio-pci,host=02:00.0,id=pcidev,romfile=allocmem.rom

I've tried debugging this further by using gdb, but so far haven't managed to
get a build that has full symbols.




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