From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Anderson Date: Sun, 26 Jan 2020 17:24:17 -0500 Subject: [PATCH v2 05/11] riscv: Add option to disable writes to mcounteren In-Reply-To: References: <3411d84b-5a56-ae4e-1deb-085ef1a4971d@gmail.com> <2eef694b-a166-3d62-bfab-a39e87cecf0a@gmail.com> Message-ID: <7c6779a3-cfa3-906b-7fd7-a8c13d6ef7a5@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 1/26/20 5:09 PM, Lukas Auer wrote: > + Bin, Anup, Atish > > > On Wed, 2020-01-15 at 17:53 -0500, Sean Anderson wrote: >> On the kendryte k210, writes to mcounteren result in an illegal instruction >> exception. >> >> Signed-off-by: Sean Anderson >> --- >> Changes for v2: >> Moved forward in the patch series >> >> arch/riscv/Kconfig | 3 +++ >> arch/riscv/cpu/cpu.c | 2 ++ >> 2 files changed, 5 insertions(+) >> >> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig >> index 9a7b0334c2..4f8c62dcff 100644 >> --- a/arch/riscv/Kconfig >> +++ b/arch/riscv/Kconfig >> @@ -226,6 +226,9 @@ config XIP >> from a NOR flash memory without copying the code to ram. >> Say yes here if U-Boot boots from flash directly. >> >> +config SYS_RISCV_NOCOUNTER >> + bool "Disable accesses to the mcounteren CSR" >> + > > Can you rename this to something like RISCV_PRIV_1_9_1? > > The k210 implements version 1.9.1 of the privileged spec (if I remember > correctly). The mcounteren CSR doesn't exist in that version and > therefore triggers the illegal instruction exception. By renaming the > config entry, it is clearer why the CSR is missing and is therefore not > accessed. Thanks, I was not aware that the k210 was following a different spec when I made the change. For v3 I can add this functionality back using the old counter CSRs. > I am not too familiar with the changes between the versions of the > spec. Are there other parts of the code we need to adapt? >From reading the changelog, most of the changes seem related to virtual memory, which doesn't apply to u-boot. --Sean