Re: [PATCH v2 06/39] xen/riscv: use UINT64_MAX to disable the VS-timer

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 9/1/26 9:12 AM, Jan Beulich wrote:
> On 27.08.2026 17:20, Oleksii Kurochko wrote:
> > vstimecmp is a 64-bit CSR independently of XLEN, which is why it is
> > written with csr_write64(). On RV32 that macro splits the value into
> > the vstimecmp/vstimecmph pair, so passing ULONG_MAX (0xffffffff there)
> > writes all ones to the low half and zero to the high half, leaving the
> > CSR at 0x00000000ffffffff rather than at its maximum. A VS-timer irq
> > would then become pending as soon as (time + htimedelta) reaches 2^32,
> > which is exactly what the code is trying to avoid.
> >
> > Use UINT64_MAX, which matches the width of the CSR. On RV64 it is equal
> > to ULONG_MAX, so no functional change there.
> Hmm. This again is an example where code (likely) will be silently wrong
> for RV128. Presumably the CSR would be XLEN bits wide there as well, and
> hence you'd need to write it with 128 bits of ones. Imo ~0 is what wants
> using here.
Agree, it makes would be better to have ~0 here. I will apply that.

Thanks.

~ Oleksii