[PATCH] Makefile: add a note about the NO_MMAP setting on IRIX and IRIX64
- From
Brandon Casey <casey@nrlssc.navy.mil>
- Date
- Oct 9, 2009, 00:09 UTC
- Message-ID
- <wTau-ugyVF7kG6Pxm7DRuWdrZABot_lbCcrG1e9aKIiNkU3X9L4ELEaLmN_rFVebheOs8fQEyx028yJUR9W-0w@cipher.nrlssc.navy.mil>
From: Brandon Casey <drafnel@gmail.com>
When git is compiled with the MIPSpro 7.4.4m compiler, and NO_PTHREADS is set, and NO_MMAP is _not_ set, then git segfaults when trying to access the first entry in a reflog. If NO_PTHREADS is not set (which implies that the pthread library is linked in), or NO_MMAP _is_ set, then the segfault is not encountered. The conservative choise has been made to set NO_MMAP in the Makefile to avoid this flaw. The GNU C compiler does not produce this behavior.
The segfault happens in refs.c:read_ref_at(). The mmap succeeds, and the loop is executed properly until rec is rewound into the first line (reflog entry) of the file. The segfault is caught by test 28 of t1400-update-ref.sh which fails when 'git rev-parse --verify "master@{May 25 2005}"' is called.
So, add a comment in the Makefile to describe why NO_MMAP is set and as a hint to those who may be interested in unsetting it.
Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil> --- Makefile | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/Makefile b/Makefile index dd3d520..a340fb1 100644 --- a/Makefile +++ b/Makefile @@ -841,6 +841,12 @@ ifeq ($(uname_S),IRIX) NO_MEMMEM = YesPlease NO_MKSTEMPS = YesPlease NO_MKDTEMP = YesPlease + # When compiled with the MIPSpro 7.4.4m compiler, and without pthreads + # (i.e. NO_PTHREADS is set), and _with_ MMAP (i.e. NO_MMAP is not set), + # git dies with a segmentation fault when trying to access the first + # entry of a reflog. The conservative choice is made to always set + # NO_MMAP. If you suspect that your compiler is not affected by this + # issue, comment out the NO_MMAP statement. NO_MMAP = YesPlease NO_EXTERNAL_GREP = UnfortunatelyYes SNPRINTF_RETURNS_BOGUS = YesPlease @@ -854,6 +860,12 @@ ifeq ($(uname_S),IRIX64) NO_MEMMEM = YesPlease NO_MKSTEMPS = YesPlease NO_MKDTEMP = YesPlease + # When compiled with the MIPSpro 7.4.4m compiler, and without pthreads + # (i.e. NO_PTHREADS is set), and _with_ MMAP (i.e. NO_MMAP is not set), + # git dies with a segmentation fault when trying to access the first + # entry of a reflog. The conservative choice is made to always set + # NO_MMAP. If you suspect that your compiler is not affected by this + # issue, comment out the NO_MMAP statement. NO_MMAP = YesPlease NO_EXTERNAL_GREP = UnfortunatelyYes SNPRINTF_RETURNS_BOGUS = YesPlease
-- 1.6.5.rc2.17.gdbc1b