On Mon, Jul 6, 2015 at 6:26 AM, Jan Beulich <jbeul...@suse.com> wrote:
> >>> On 30.06.15 at 16:48, <tleng...@novetta.com> wrote: > >> > --- a/xen/include/asm-x86/domain.h > > > >> >> +++ b/xen/include/asm-x86/domain.h > >> >> @@ -342,13 +342,15 @@ struct arch_domain > >> >> > >> >> /* Monitor options */ > >> >> struct { > >> >> - uint16_t write_ctrlreg_enabled : 4; > >> >> - uint16_t write_ctrlreg_sync : 4; > >> >> - uint16_t write_ctrlreg_onchangeonly : 4; > >> >> - uint16_t mov_to_msr_enabled : 1; > >> >> - uint16_t mov_to_msr_extended : 1; > >> >> - uint16_t singlestep_enabled : 1; > >> >> - uint16_t software_breakpoint_enabled : 1; > >> >> + uint32_t write_ctrlreg_enabled : 4; > >> >> + uint32_t write_ctrlreg_sync : 4; > >> >> + uint32_t write_ctrlreg_onchangeonly : 4; > >> >> + uint32_t mov_to_msr_enabled : 1; > >> >> + uint32_t mov_to_msr_extended : 1; > >> >> + uint32_t singlestep_enabled : 1; > >> >> + uint32_t software_breakpoint_enabled : 1; > >> >> + uint32_t request_enabled : 1; > >> >> + uint32_t request_sync : 1; > >> > > >> > Can you please switch to plain unsigned int if you already have to > >> > touch this? There's no reason I can see to use a fixed width integer > >> > type here. > >> > >> Ack, will make it plain int. > > > > > > IMHO having it fix-width is easier to read when adding new elements to > see > > how many bits we have left free. I would not want this changed unless > there > > is a clear benefit to doing so. > > I can't see what benefit using fixed widht types here is: Best > demonstrated with uint64_t, gcc doesn't honor the type of the > field anyway. And hence counting the number of left bits (with > some unknown definition of "left") is quite pointless too - it's an > internal structure, and when a new bit field needs to be added, > it doesn't really matter whether it grows the structure (at least > no more than any other field addition). > > Bottom line - no fixed width types when not really warranted, > please. > > Jan > SGTM. Thanks, Tamas
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