On 04/02/2019 14:35, Bhupesh Sharma wrote: [...]
Also hardcoding the PTE calculation to use the high address bit mask always will break the backward compatibility with older kernels (which don't support 52-bit address space extensions).
No it won't. There's no difference between an old kernel, a new kernel on a CPU without ARMv8.2-LPA, or a new kernel on a CPU with ARMv8.2-LPA in a system which happens to have less than 49 bits of physical memory map - in all those cases the relevant bits are either RES0 or just actually 0 in the PTE, so replacing 4 bits of zeros with 4 bits of other zeros in the final physical address has no effect whatsoever other than taking a couple of extra instructions to perform.
If you're running a 64K page kernel on a system with an SMMU, note how that's already been "broken" for nearly a year now ;)
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/iommu/io-pgtable-arm.c#n211 Robin. _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
