From: Konstantin Khorenko <khorenko@virtuozzo.com>
To: devel@openvz.org, Konstantin Khorenko <khorenko@virtuozzo.com>
Subject: [Devel] [PATCH vz10] configs: Build CONFIG_CRYPTO_CRC32C_INTEL in, not as a module
Date: Mon, 14 Sep 2026 19:51:19 +0200 [thread overview]
Message-ID: <20260914-temp2-v1-1-07379e4ed812@virtuozzo.com> (raw)
lib/libcrc32c.c binds a static tfm once, in libcrc32c_mod_init(), a
device_initcall that runs early at boot. With CRYPTO_CRC32C_INTEL=m the
accelerated driver has not registered yet, so the tfm binds to
crc32c-generic and keeps it: loading the module later cannot rebind it,
it just sits there unused. Every crc32c() caller then runs the software
crc32_body path instead of the CPU's CRC32 instruction, which lands on
every ext4/xfs/btrfs/nvme/dm-integrity checksum.
Building the driver in makes its initcall run before
libcrc32c_mod_init(), since arch/x86/ links before lib/ and both are
device_initcall. The tfm then binds to crc32c-intel from the first
allocation.
This does not remove the crypto shash wrapper crc32c() still goes
through; a direct arch-dispatch implementation would still be faster.
https://virtuozzo.atlassian.net/browse/VSTOR-145125
Feature: crc32c: hardware-accelerated checksum
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
---
redhat/configs/custom-overrides/generic/CONFIG_CRYPTO_CRC32C_INTEL | 1 +
1 file changed, 1 insertion(+)
diff --git a/redhat/configs/custom-overrides/generic/CONFIG_CRYPTO_CRC32C_INTEL b/redhat/configs/custom-overrides/generic/CONFIG_CRYPTO_CRC32C_INTEL
new file mode 100644
index 0000000000000..d4f84f727c85c
--- /dev/null
+++ b/redhat/configs/custom-overrides/generic/CONFIG_CRYPTO_CRC32C_INTEL
@@ -0,0 +1 @@
+CONFIG_CRYPTO_CRC32C_INTEL=y
---
base-commit: ef994d2c62a1d045543fe80aaf584139b22fbaf7
change-id: 20260914-temp2-fe6929d95c5d
Best regards,
--
Konstantin Khorenko <khorenko@virtuozzo.com>
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next reply other threads:[~2026-09-14 17:53 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-14 17:51 Konstantin Khorenko [this message]
2026-09-14 17:54 ` Konstantin Khorenko
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