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authorThomas Chou <thomas@wytron.com.tw>2010-05-21 11:08:03 +0800
committerScott McNutt <smcnutt@psyent.com>2010-05-28 10:56:03 -0400
commit0df01fd3d71481b5cc7aeea6a741b9fc3be15178 (patch)
treea5eb637453d7f400eb1f9709b376ad247905e265 /doc
parent661ba14051db6766932fcb50ba1ec7c67f230054 (diff)
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 'doc')
-rw-r--r--doc/README.standalone13
1 files changed, 7 insertions, 6 deletions
diff --git a/doc/README.standalone b/doc/README.standalone
index 885c92fb3..638108749 100644
--- a/doc/README.standalone
+++ b/doc/README.standalone
@@ -19,12 +19,12 @@ Design Notes on Exporting U-Boot Functions to Standalone Applications:
thus the compiler cannot perform type checks on these assignments.
2. The pointer to the jump table is passed to the application in a
- machine-dependent way. PowerPC, ARM, MIPS and Blackfin architectures
- use a dedicated register to hold the pointer to the 'global_data'
- structure: r2 on PowerPC, r8 on ARM, k0 on MIPS, and P3 on Blackfin.
- The x86 architecture does not use such a register; instead, the
- pointer to the 'global_data' structure is passed as 'argv[-1]'
- pointer.
+ machine-dependent way. PowerPC, ARM, MIPS, Blackfin and Nios II
+ architectures use a dedicated register to hold the pointer to the
+ 'global_data' structure: r2 on PowerPC, r8 on ARM, k0 on MIPS,
+ P3 on Blackfin and gp on Nios II. The x86 architecture does not
+ use such a register; instead, the pointer to the 'global_data'
+ structure is passed as 'argv[-1]' pointer.
The application can access the 'global_data' structure in the same
way as U-Boot does:
@@ -56,6 +56,7 @@ Design Notes on Exporting U-Boot Functions to Standalone Applications:
ARM 0x0c100000 0x0c100000
MIPS 0x80200000 0x80200000
Blackfin 0x00001000 0x00001000
+ Nios II 0x02000000 0x02000000
For example, the "hello world" application may be loaded and
executed on a PowerPC board with the following commands: