> On Tue, Jan 20, 2026 at 05:59:47PM +0000, Yeoreum Yun wrote: > > On second thought, while a CPU that implements LSUI is unlikely to > > support AArch32 compatibility, > > I don't think LSUI requires the absence of AArch32. > > These two are independent features (and in fact our FVP reports/supports > > both). > > Did you have to configure the FVP specially for this or that a "default" > configuration? > > > Given that, I'm not sure a WARN is really necessary. > > Would it be sufficient to just drop the patch for swpX instead? > > Given that the whole point of LSUI is to remove the PAN toggling, I think > we should make an effort to make sure that we don't retain PAN toggling > paths at runtime that could potentially be targetted by attackers. If we > drop the SWP emulation patch and then see that we have AArch32 at runtime, > we should forcefully disable the SWP emulation but, since we don't actually > think we're going to see this in practice, the WARN seemed simpler.
TBH, I missed the FVP configuration option clusterX.max_32bit_el, which can disable AArch32 support by setting it to -1 (default: 3). Given this, I think it’s reasonable to emit a WARN when LSUI is enabled and drop the SWP emulation path under that condition. Thanks! -- Sincerely, Yeoreum Yun
