Re: [PATCH V2] efi_high_alloc: use EFI_ALLOCATE_MAX_ADDRESS

From: Matt Fleming
Date: Wed Aug 27 2014 - 06:30:47 EST

On Mon, 25 Aug, at 04:33:54PM, Harald Hoyer wrote:
> So is that ok, if other callers of efi_high_alloc() get an address >
> 4GB?

Yeah, the issue at hand is that some x86 EFI firmware cannot perform a
file read into a buffer above 4G. The actual allocation works fine.

If other callers want a high address buffer, they're not going to hit
that issue. We've no reason to believe that this bug affects arm64 at
all, for instance.

Working around this problem in efi_high_alloc() gives the impression
that there's something wrong with AllocatePages(), which isn't the case.

> Will the buggy EFI implementation work with the usage of the other
> caller's allocated memory? Or will they run into the same issues as
> the initramfs loader?

Based on the information we've gathered so far, there's no reason to
believe other callers will hit the same issue as the file reading code.

Matt Fleming, Intel Open Source Technology Center
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