diff options
| author | Jonathan Neuschäfer <j.neuschaefer@gmx.net> | 2016-06-10 19:35:15 +0200 |
|---|---|---|
| committer | Martin Roth <martinroth@google.com> | 2016-06-12 12:42:32 +0200 |
| commit | 1282b8d99692ddfff5b78b03938b9b3555b17c00 (patch) | |
| tree | c8141a7cd0789c9b24c4da9a7065312fe13fefa1 /src/arch/riscv | |
| parent | f934efc9f8e2fe0791f47e7088301199629827b1 (diff) | |
arch/riscv: Compile with -mcmodel=medany
In the default (medlow) code model, pointers are loaded with a lui, addi
instruction sequence:
lui a0, 0xNNNNN
addi a0, a0, 0xNNN
Since lui sign-extends bits 32-63 from bit 31 on RV64, lui/addi can't
load pointers just above 0x80000000, where RISC-V's RAM now lives.
The medany code model gets around this restriction by loading pointers
trough auipc and addi:
auipc a0, 0xNNNNN
addi a0, a0, 0xNNN
This way, any pointer within the current pc ±2G can be loaded, which is
by far sufficient for coreboot.
Change-Id: I77350d9218a687284c1337d987765553cf915a22
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/15148
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Diffstat (limited to 'src/arch/riscv')
| -rw-r--r-- | src/arch/riscv/Makefile.inc | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/src/arch/riscv/Makefile.inc b/src/arch/riscv/Makefile.inc index 4521dcbba6..243fa5364e 100644 --- a/src/arch/riscv/Makefile.inc +++ b/src/arch/riscv/Makefile.inc @@ -15,7 +15,7 @@ ## ################################################################################ -riscv_flags = -I$(src)/arch/riscv/ +riscv_flags = -I$(src)/arch/riscv/ -mcmodel=medany riscv_asm_flags = @@ -48,6 +48,9 @@ $(objcbfs)/bootblock.debug: $$(bootblock-objs) -T $(call src-to-obj,bootblock,src/mainboard/$(MAINBOARDDIR)/memlayout.ld) --whole-archive --start-group $(filter-out %.ld,$(bootblock-objs)) \ $(LIBGCC_FILE_NAME_bootblock) --end-group $(COMPILER_RT_bootblock) +bootblock-c-ccopts += $(riscv_flags) +bootblock-S-ccopts += $(riscv_asm_flags) + endif ################################################################################ |