Date: Mon, 9 Feb 1998 05:49:52 -0600 From: Richard Wackerbarth <rkw@dataplex.net> To: Eivind Eklund <eivind@yes.no> Cc: Michael Hancock <michaelh@cet.co.jp>, FreeBSD Hackers <Hackers@FreeBSD.ORG> Subject: Re: DIAGNOSTICS and DEBUG LOGGING (was Re: cvs commit: src/sys/conf options) Message-ID: <l03130304b1049a4c285d@[208.2.87.4]> In-Reply-To: <19980209091644.21614@follo.net> References: <Pine.SV4.3.95.980209160831.661B-100000@parkplace.cet.co.jp>; from Michael Hancock on Mon, Feb 09, 1998 at 04:27:14PM %2B0900 <19980209075127.63680@follo.net> <Pine.SV4.3.95.980209160831.661B-100000@parkplace.cet.co.jp>
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At 2:16 AM -0600 2/9/98, Eivind Eklund wrote:
>> > _ASSERTS - Enable precondition and other cheap assertions
>> > _INVARIANTS - Enable invariant/postcondition checking (expensive)
>> > INVARIANT_CODE - Compile in invariant functions.
>>
>> So we have 3 levels of "sanity checking" with increasing levels of cost.
>> I like it, it's a good fit to how people want to use assertions in
>> practice.
>
>Just to make this perfectly clear (I'm not certain if you got my
>meaning or not):
>
>Enabling INVARIANT_CODE will not add _any_ checks to the kernel.
INVARIANT_SUPPORT
>Instead, it will add the code that is necessary to enable any checks
>at will. If INVARIANT_CODE is defined for the entire kernel, then
>_ASSERTS or _INVARIANTS can be defined for any single file without any
>compilation trouble, even if _ASSERTS/_INVARIANTS isn't enabled for
>any other file.
Let me suggest something that I found to work well in developing drivers
on MacOS. Rather than fill the code with
#ifdef _ASSERTS
if ((unsigned long)cblockp & (CBLOCK-1))
panic("Unaligned cblock in cblock_free");
#endif
how about
ASSERT(((unsigned long)cblockp & (CBLOCK-1)), "Unaligned cblock in
cblock_free");
Then you can hide the _ASSERTS stuff in a header which defines the ASSERT macro
and get rid of the clutter in the code.
#ifdef _ASSERTS
#define ASSERT(X,Y) if (X) panic(Y)
#else
#define ASSERT(X,Y)
#endif
Richard Wackerbarth
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