tree c10207febe260530dfb7c733912994599a9594bf
parent e0e102ee24bdab68b0318b505402f60cfb88a5f0
author Michael Brown <mcb30@ipxe.org> 1730156336 +0000
committer Michael Brown <mcb30@ipxe.org> 1730156834 +0000

[riscv] Check if seed CSR is accessible from S-mode

The seed CSR defined by the Zkr extension is accessible only in M-mode
by default.  Older versions of OpenSBI (prior to version 1.4) do not
set mseccfg.sseed, with the result that attempts to access the seed
CSR from S-mode will raise an illegal instruction exception.

Add a facility for testing the accessibility of arbitrary CSRs, and
use it to check that the seed CSR is accessible before reporting the
seed CSR entropy source as being functional.

Signed-off-by: Michael Brown <mcb30@ipxe.org>