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Enhanced printk() mergedEnhanced printk() mergedPosted Jul 17, 2008 8:59 UTC (Thu) by meuh (subscriber, #22042)Parent article: Enhanced printk() merged
Strange way to specify format. According to printf() manual page: Each conversion specification is introduced by the '%' character [...] after which the following appear in sequence:
So, the correct way to specify a struct inode pointer should be %Ip, where I is the flag and p the conversion specifier. Did kernel developers read userland manual pages ? :)
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Enhanced printk() merged Posted Jul 17, 2008 9:56 UTC (Thu) by nix (subscriber, #2304) [Link] If they used that format, GCC would warn about it. The format chosen looks to GCC (as to userland printf()) like a %p with unrelated characters after it, so GCC doesn't check those unrelated characters because they're just literal text as far as it knows.
Enhanced printk() merged Posted Jul 17, 2008 16:41 UTC (Thu) by meuh (subscriber, #22042) [Link] Extending GCC to support some new kind of format string is also possible, sadly this can't be done dynamically, patching GCC is required. GCC already knows about other format string, see: http://gcc.gnu.org/onlinedocs/gcc-4.3.0/gcc/Target-Format... http://gcc.gnu.org/onlinedocs/gcc-4.3.0/gcc/Function-Attr...
Enhanced printk() merged Posted Jul 17, 2008 17:41 UTC (Thu) by nix (subscriber, #2304) [Link] Yes indeed, and printk() is marked up with the printf attribute. The trick is to find a way to define new format characters that doesn't cause GCC to warn about all of them. There were attempts in the past to make the format attributes dynamically redefinable, but if I recall correctly the consensus in the end was that this was simply too damn complicated. (I wonder if what we need is loose versions of the format attribute's archetypes, which warn about incorrect numbers of parameters and type mismatches for format letters GCC knows about, but does not check format letters that GCC doesn't know? As long as nobody tries to reimplement something like .* which changes the number of arguments consumed, this should work fine.)
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