I found zstd in /drivers/block/zram/zcomp.c, but I can't find anything zstd-related in /crypto. So is zstd for zram actually available in Linux 4.15 or not?

1 Answer 1


It’s supposed to be available in 4.15, as long as the CONFIG_CRYPTO_ZSTD setting is enabled. The implementation lives in lib/zstd.

However the zram integration expects to find zstd via the crypto API, as you discovered, and that part’s missing — which explains why there’s no way to actually enable CRYPTO_ZSTD, and why there’s no code registering zstd with the crypto framework.


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