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| author | Thomas Chou <thomas@wytron.com.tw> | 2010-05-21 11:08:03 +0800 |
|---|---|---|
| committer | Scott McNutt <smcnutt@psyent.com> | 2010-05-28 10:56:03 -0400 |
| commit | 0df01fd3d71481b5cc7aeea6a741b9fc3be15178 (patch) | |
| tree | a5eb637453d7f400eb1f9709b376ad247905e265 /README | |
| parent | 661ba14051db6766932fcb50ba1ec7c67f230054 (diff) | |
| download | talos-obmc-uboot-0df01fd3d71481b5cc7aeea6a741b9fc3be15178.tar.gz talos-obmc-uboot-0df01fd3d71481b5cc7aeea6a741b9fc3be15178.zip | |
nios2: fix r15 issue for gcc4
The "-ffixed-r15" option doesn't work well for gcc4. Since we
don't use gp for small data with option "-G0", we can use gp
as global data pointer. This allows compiler to use r15. It
is necessary for gcc4 to work properly.
Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Signed-off-by: Scott McNutt <smcnutt@psyent.com>
Diffstat (limited to 'README')
| -rw-r--r-- | README | 8 |
1 files changed, 8 insertions, 0 deletions
@@ -4023,6 +4023,14 @@ On ARM, the following registers are used: ==> U-Boot will use R8 to hold a pointer to the global data +On Nios II, the ABI is documented here: + http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf + + ==> U-Boot will use gp to hold a pointer to the global data + + Note: on Nios II, we give "-G0" option to gcc and don't use gp + to access small data sections, so gp is free. + NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope, or current versions of GCC may "optimize" the code too much. |
