On Mon, Jun 19, 2023 at 1:36 PM Marco Elver <elver@xxxxxxxxxx> wrote: > > On Mon, 19 Jun 2023 at 12:15, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > > On Mon, 19 Jun 2023 at 12:12, Chanho Min <chanho.min@xxxxxxx> wrote: > > > > > > This patch removes description of the KASAN_HW_TAGS's memory consumption. > > > KASAN_HW_TAGS does not set 1/32nd shadow memory. > > > > The hardware still allocates/uses shadow in MTE. > > Though, it may be 1/16-th, not sure. 1/32 is correct: 4 bits for every 16 bytes. > I think the point is that it depends on the hardware implementation of > MTE. There are a range of possibilities, but enabling KASAN_HW_TAGS > doesn't consume any extra memory for tags itself if the hardware has > to enable MTE and provision tag space via firmware to begin with. Yeah, saying that HW_TAGS consumes memory is wrong. But it might reasonable to spell out what happens with memory in the config options description. Something like: "Does not consume memory by itself but relies on the 1/32nd of available memory being reserved by the firmware when MTE is enabled."
