Bug#834505: arm64 boot failure with large physical memory range
On Sun, 2016-08-21 at 11:42 +0100, Leif Lindholm wrote:
>
> You're not wrong, but unfortunately the ability to write semi-portable
> code left the planet over a decade ago. For clarification - the
> problem is not with regards to code written specifically for arm64 and
> not verified with different MMU-configurations, but with code written
> for x86 and never tested on anything else.
Wouldn't the equivalent scenario on x86 result in taking faults (#GP
IIRC) due to them being non-canonical addresses? (Which are basically
Intel's way of forbidding the use of bits above the physical address
size when registers are used in pointer-like ways, i.e. for
loads/stores or jump targets etc).
I thought there was a control bit on ARMv8 too which made it cause a
fault if the code loaded through, stored via, branched to etc an
address with bits set between the maximum physical address bit and the
bits architecturally reserved for tagging at the top end of the word,
but perhaps my memory has simply fabricated that out of thing air?
Ian.
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