Re: Making MAX_PHYS_ADDRESS_BITS configurable
On 5/24/19 6:20 PM, David Miller wrote:
>> On the other hand, arm64 currently allows the virtual address size
>> to be configurable, currently defaulting to 48 bits [2, 3]. I was
>> therefore wondering whether we could make MAX_PHYS_ADDRESS_BITS [4]
>> configurable as well to be able to support these JITs on
>> Debian/sparc64 for the foreseeable future by limiting the virtual
>> address space to 47 or 48 bits.
>
> You can't just do this.
>
> It is possible that all physical memory is mapped to the top of the
> mappable physical address range, therefore we really need to use the
> full maximum setting supported by the CPU.
Yes, my initial mail was incorrect. What I actually meant was reducing
the size of the va_hole in userspace so that the top-most address that
mmap() would return is not beyond 2^47.
Would it be possible to add such a workaround until the JITs have fixed
their broken code?
Adrian
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer - glaubitz@debian.org
`. `' Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
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