Messages in this thread | | | Date | Fri, 16 Mar 2007 14:56:24 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [patch 17/26] Xen-paravirt_ops: Add nosegneg capability to the vsyscall page notes |
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Roland McGrath wrote: > This should be: > > NOTE_KERNELCAP_BEGIN(1, 1) > NOTE_KERNELCAP(0, "nosegneg") > NOTE_KERNELCAP_END > > i.e. 1->0 in the "bit" member. (Note the ld.so.conf.d file must have the > matching bit number for ldconfig-based lookups to do the right thing.) > Or else: > > NOTE_KERNELCAP_BEGIN(1, 2) > NOTE_KERNELCAP(0, "nosegneg") > NOTE_KERNELCAP_END > > i.e. 1->2 in the "mask" member. (The mask value should be 1<<bit.) >
Thanks Roland. I've never really understood this stuff, and I just copied this cargo-cultishly.
I'm not quite sure what you're suggesting here though. Do you mean one of:
NOTE_KERNELCAP_BEGIN(1, 1) NOTE_KERNELCAP(0, "nosegneg") NOTE_KERNELCAP_END
or
NOTE_KERNELCAP_BEGIN(1, 2) NOTE_KERNELCAP(1, "nosegneg") NOTE_KERNELCAP_END
is the correct thing to use?
> Some pre-release glibc's (before 2.4) had a bug in the code that parses > this, and would crash parsing the correct note. Using the wrong bit value > with nonmatching mask worked around this. IIRC, no glibc release ever > included the buggy version of the code. In nonbuggy glibc, the mismatched > value causes the "nosegneg" to be omitted from the directory search (under > LD_LIBRARY_PATH and default directories), though ldconfig-based lookups > will work (the most common case). >
Are you saying that one of the corrected forms might cause old glibcs to crash, or just ignore nosegneg?
J
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