Date: Tue, 19 May 2015 00:28:05 -0500 From: Pedro Giffuni <pfg@FreeBSD.org> To: Bruce Evans <brde@optusnet.com.au> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r283088 - head/sys/ddb Message-ID: <BA474AEC-A0A8-4FF8-8881-397E8280C72F@FreeBSD.org> In-Reply-To: <20150519135341.R2157@besplex.bde.org> References: <201505182227.t4IMRljx078812@svn.freebsd.org> <20150519113755.U1840@besplex.bde.org> <406A7AE3-1891-4B2C-B917-14C150EBBAB5@FreeBSD.org> <20150519135341.R2157@besplex.bde.org>
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> Il giorno 18/mag/2015, alle ore 23:34, Bruce Evans <brde@optusnet.com.au> ha scritto: > > On Mon, 18 May 2015, Pedro Giffuni wrote: > >>> Il giorno 18/mag/2015, alle ore 20:48, Bruce Evans <brde@optusnet.com.au> ha scritto: >>> >>> On Mon, 18 May 2015, Pedro F. Giffuni wrote: >>> >>>> Log: >>>> ddb: stop boolean screaming. >>>> >>>> TRUE --> true >>>> FALSE--> false >>>> >>>> Hinted by: NetBSD >>> >>> This is not just churn to a style regression, but a type mismatch. >> >> It is an attempt to reduce differences with NetBSD. > > For that, apply the reverse change to NetBSD. > Actually, the NetBSD code uses bool. (I hate CVS, commits are not atomic.) >> One of the complaints of hear from newcomers to the ddb code is that >> the format is old-fashioned (it still had pre-ANSI headers not long ago) >> and unmaintained. > > It is fairly well maintained (not churned to unimprove its portability). > Why would newcomers want too look at it? > Unrelated fun: last year a student started adding support for CTF and pretty printing of the kernel structures. I think the NetBSD guys have been having fun with Lua. >>>> Modified: head/sys/ddb/db_break.c >>>> ============================================================================== >>>> --- head/sys/ddb/db_break.c Mon May 18 22:14:06 2015 (r283087) >>>> +++ head/sys/ddb/db_break.c Mon May 18 22:27:46 2015 (r283088) >>>> @@ -155,12 +155,12 @@ db_find_breakpoint_here(db_addr_t addr) >>>> return db_find_breakpoint(db_map_addr(addr), addr); >>>> } >>>> >>>> -static boolean_t db_breakpoints_inserted = TRUE; >>>> +static boolean_t db_breakpoints_inserted = true; >>> >>> This code hasn't been churned to use the boolean type. It still uses >>> boolean_t, which is plain int. TRUE and FALSE go with this type. true >>> and false go with the boolean type. This probably makes no difference, >>> because TRUE happens to be implemented with the same value as true and >>> there are lots of implicit versions between the types. >> >> Yes, I noticed the return types are still ints. It doesn’t look difficult >> to convert it to use a real boolean type. In any case, I would prefer to go >> forward (using bool) instead of reverting this change. > > That wuld be sideways. > > I forgot to mention (again) in my previous reply that boolean_t is a mistake > by me. KNF code doesn't even use the ! operator, but uses explicit > comparison with 0. The boolean_t type and TRUE and FALSE are from Mach. > They were used mainly in ddb and vm, and are still almost never used in > kern. I used to like typedefs and a typedef for boolean types, and didn't > know KNF very well, so in 1995 I moved the declaration of boolean_t from > Mach vm code to sys/types.h to try to popularize it. This was a mistake. > Fortunately, it is still rarely used in core kernel code. > > The boolean type is also almost never used for syscalls. In POSIX.1-2001, > <stdbool.h> is inherited from C99, but is never used for any other POSIX > API. Using it for syscalls would mainly cause portability problems. > OK, I do understand the kernel wants to keep the C dialect somewhat limited, and adding stdbool.h doesn’t buy us any type safety here. I’ll revert the change (prob. tomorrow though). Pedro.
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