On 22/06/2021 16:19, Jan Beulich wrote: > Some sub-functions, XENMEM_maximum_gpfn and XENMEM_maximum_ram_page in > particular, can return values requiring more than 31 bits to represent. > Hence we cannot issue the hypercall directly when the return value of > ioctl() is used to propagate this value (note that this is not the case > for the BSDs, and MiniOS already wraps all hypercalls in a multicall).
It took me 3 readings to realise you weren't saying that BSDs used multicall (which they don't). Instead, I'd suggest rewording it. "Some sub-functions, XENMEM_maximum_gpfn and XENMEM_maximum_ram_page in particular, can return values requiring more than 31 bits to represent. The BSDs deliberately avoid using the ioctl() return value, and MiniOS already uses a multicall. They aren't affected. Linux and Solaris however do use the ioctl() return value, which must be avoided in this case to avoid truncation." Or something similar. With a suitable improvement along these lines, Acked-by: Andrew Cooper <andrew.coop...@citrix.com>
