On Mon, Mar 25, 2024 at 11:10:49AM +0800, Yangyu Chen wrote: > > On Mar 25, 2024, at 00:23, Icenowy Zheng <uwu@xxxxxxxxxx> wrote: > > 在 2024-03-23星期六的 20:12 +0800，Yangyu Chen写道： > >> - Svpbmt and T-Head MAEE both supported > >> > >> T-Head C908 does support both Svpbmt and T-Head MAEE for page-based > >> memory > >> attributes and is controlled by BIT(21) on CSR.MXSTATUS. The Svpbmt > >> is used > >> here for mainline kernel support for K230. If the kernel wants to use > >> Svpbmt, the M-Mode software should unset BIT(21) of CSR.MXSTATUS > >> before > >> entering the S-Mode kernel. Otherwise, the kernel will not boot, as 0 > >> on > >> T-Head MAEE is NonCachable Memory. Once the kernel switches from bare > >> metal > >> to Sv39, It will lose dirty cache line modifications that haven't > >> been > >> written back to the memory. > > > > As MXSTATUS has a S-mode read-only mirror known as SXSTATUS, maybe the > > kernel should detect SXSTATUS to decide whether to use Svpbmt or > > Xtheadpbmt (BTW Svnapot conflicts with Xtheadpbmt too). > > > > Thanks for this hint. I may need to change some code in the T-Head PBMT probe. For now, I'd rather we just focused on supporting the standard extensions on this SoC in mainline. I've applied the patches re-doing the Kconfig options just now, feel free to resend these patches whenever. Thanks, Conor.
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