On Tue, Jun 04, 2024 at 01:44:15PM +0200, Alexandre Ghiti wrote: > On Tue, Jun 4, 2024 at 10:52 AM Conor Dooley <conor@xxxxxxxxxx> wrote: > > > > On Tue, Jun 04, 2024 at 09:17:26AM +0200, Alexandre Ghiti wrote: > > > On Tue, Jun 4, 2024 at 9:15 AM Alexandre Ghiti <alexghiti@xxxxxxxxxxxx> wrote: > > > > On Tue, Jun 4, 2024 at 8:21 AM yunhui cui <cuiyunhui@xxxxxxxxxxxxx> wrote: > > > > > > > > > > As for the current status of the patch, there are two points that can > > > > > be optimized: > > > > > 1. Some chip hardware implementations may not cache TLB invalid > > > > > entries, so it doesn't matter whether svvptc is available or not. Can > > > > > we consider adding a CONFIG_RISCV_SVVPTC to control it? > > > > > > That would produce a non-portable kernel. But I'm not opposed to that > > > at all, let me check how we handle other extensions. Maybe @Conor > > > Dooley has some feedback here? > > > > To be honest, not really sure what to give feedback on. Could you > > elaborate on exactly what the option is going to do? Given the > > portability concern, I guess you were proposing that the option would > > remove the preventative fences, rather than your current patch that > > removes them via an alternative? > > No no, I won't do that, we need a generic kernel for distros so that's > not even a question. What Yunhui was asking about (to me) is: can we > introduce a Kconfig option to always remove the preventive fences, > bypassing the use of alternatives altogether? > > To me, it won't make a difference in terms of performance. But if we > already offer such a possibility for other extensions, well I'll do > it. Otherwise, the question is: should we start doing that? We don't do that for other extensions yet, because currently all the extensions we have options for are additive. There's like 3 alternative patchsites, and they are all just one nop? I don't see the point of having a Kconfig knob for that.
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