On 22.01.2020 22:31, Andrew Cooper wrote: > On 22/01/2020 20:23, Wei Liu wrote: >> --- a/xen/arch/x86/e820.c >> +++ b/xen/arch/x86/e820.c >> + */ >> + unsigned int phys_bits = find_phys_addr_bits(); >> + unsigned long hcall_pfn = >> + ((1ull << phys_bits) - 1) >> PAGE_SHIFT; > > (1ull << (phys_bits - PAGE_SHIFT)) - 1 is equivalent, and doesn't > require a right shift. I don't know if the compiler is smart enough to > make this optimisation automatically.
It's not allowed to, without having a way to know that phys_bits is no less than PAGE_SHIFT. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
