On Mon, 28 Jan 2019 at 21:08, Richard Henderson <richard.hender...@linaro.org> wrote: > > On 1/22/19 5:26 AM, Peter Maydell wrote: > >> + guarded |= extract64(descriptor, 50, 1); /* GP */ > > > > Do we need to do the logical-OR here? Since this is a > > block/page entry bit with no similar bit in the table > > descriptors, there's no merging to be done (ie we > > only execute this code once and 'guarded' will always > > be 'false' before execution of the |=.) > > The document that I have has exactly one sentence about this, and does not > specify whether the bit is akin to the page table attributes (which appear at > every table level) or not.
Translation table descriptor formats come in four flavours: * Invalid * Table (which gives the address of the next level table) * Block (which gives the address of a large lump of memory) * Page (which gives the address of a page) The GP bit documented to be in Block and Page entries, not Table (which is how you've coded it). > As written above, this will execute more than once. I don't see how -- all the code paths forward from "guarded |= extract64(descriptor, 50, 1);" reach a "break" statement that terminates the loop, don't they? thanks -- PMM
