On 11.05.2023 19:09, Oleksii Kurochko wrote: > --- a/xen/arch/riscv/include/asm/config.h > +++ b/xen/arch/riscv/include/asm/config.h > @@ -4,6 +4,42 @@ > #include <xen/const.h> > #include <xen/page-size.h> > > +/* > + * RISC-V64 Layout: > + * > + * #ifdef SV39
I did point you at x86'es similar #ifdef. Unlike here, there we use a symbol which actually has a meaning, allowing to spot this comment in e.g. grep output when looking for uses of that symbol. Hence here e.g. #ifdef RV_STAGE1_MODE == SATP_MODE_SV39 ? (I would also recommend to use the same style as x86 does, such that the #ifdef and #endif look like normal directives [e.g. again in grep output], leaving aside that they're inside a comment.) > + * From the riscv-privileged doc: > + * When mapping between narrower and wider addresses, > + * RISC-V zero-extends a narrower physical address to a wider size. > + * The mapping between 64-bit virtual addresses and the 39-bit usable > + * address space of Sv39 is not based on zero-extension but instead > + * follows an entrenched convention that allows an OS to use one or > + * a few of the most-significant bits of a full-size (64-bit) virtual > + * address to quickly distinguish user and supervisor address regions. > + * > + * It means that: > + * top VA bits are simply ignored for the purpose of translating to PA. > + * > + * > ============================================================================ > + * Start addr | End addr | Size | Slot |area > description > + * > ============================================================================ > + * FFFFFFFFC0800000 | FFFFFFFFFFFFFFFF |1016 MB | L2 511 | Unused > + * FFFFFFFFC0600000 | FFFFFFFFC0800000 | 2 MB | L2 511 | Fixmap > + * FFFFFFFFC0200000 | FFFFFFFFC0600000 | 4 MB | L2 511 | FDT > + * FFFFFFFFC0000000 | FFFFFFFFC0200000 | 2 MB | L2 511 | Xen > + * ... | 1 GB | L2 510 | Unused > + * 0000003200000000 | 0000007f40000000 | 309 GB | L2 200-509 | Direct map The upper bound here is 0000007f80000000 afaict, which then also makes the earlier gap 1Gb in size. Jan
