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Ratified on Apr. 2024, the original RISC-V "A" extension is now split
into two separate extensions, "Zaamo" for atomic operations and "Zalrsc"
for load-reserved/store-conditional instructions.
For now, we've already seen real-world designs implement the Zalrsc
extension only[2]. As U-Boot mainly runs with only one HART, we could
easily support these designs by not using AMO instructions in the
hard-written assembly if necessary, for which this patch introduces two
new Kconfig options to indicate the availability of "Zaamo" and "Zalrsc".
Note that even with this patch, "A" extension is specified in the ISA
string passed to the compiler as long as one of "Zaamo" or "Zalrsc" is
available, since they're only recognized with a quite recent version of
GCC/Clang. The compiler usually doesn't automatically generate atomic
instructions unless the source explicitly instructs it to do so, thus
this should be safe.
Link: https://github.com/riscv/riscv-zaamo-zalrsc/commit/d94c64c63e9120d56bdeb540caf2e5dae60a8126 # [1]
Link: https://lore.kernel.org/u-boot/[email protected]/ # [2]
Signed-off-by: Yao Zi <[email protected]>
Reviewed-by: Leo Yu-Chi Liang <[email protected]>
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It is confusing to have both "$(PHASE_)" and "$(XPL_)" be used in our
Makefiles as part of the macros to determine when to do something in our
Makefiles based on what phase of the build we are in. For consistency,
bring this down to a single macro and use "$(PHASE_)" only.
Signed-off-by: Tom Rini <[email protected]>
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Use XPL_ as the symbol to indicate an SPL build. This means that SPL_ is
no-longer set.
Signed-off-by: Simon Glass <[email protected]>
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When debugging, it is useful to have a backtrace to find
out what is in the call stack as the previous function (RA)
may not have been the culprit.
Since this adds size to the build, do not add it by default
and avoid putting it in the SPL build if not needed.
Signed-off-by: Ben Dooks <[email protected]>
Tested-by: Leo Yu-Chi Liang <[email protected]>
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This patch adds ISA string to the -march to generate zbb instructions
for U-Boot binaries, along with optimized string functions introduced
from Linux kernel.
Signed-off-by: Yu Chien Peter Lin <[email protected]>
Reviewed-by: Leo Yu-Chi Liang <[email protected]>
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The riscv32 toolchain for GCC-12 provided by kernel.org contains libgcc.a
compiled for double-float. To link to it we have to adjust how we build
U-Boot.
As U-Boot actually does not use floating point at all this should not
make a significant difference for the produced binaries.
Signed-off-by: Heinrich Schuchardt <[email protected]>
Reviewed-by: Rick Chen <[email protected]>
Reviewed-by: Leo Yu-Chi Liang <[email protected]>
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The following description is copied from the equivalent patch for the
Linux Kernel proposed by Aurelien Jarno:
>From version 2.38, binutils default to ISA spec version 20191213. This
means that the csr read/write (csrr*/csrw*) instructions and fence.i
instruction has separated from the `I` extension, become two standalone
extensions: Zicsr and Zifencei. As the kernel uses those instruction,
this causes the following build failure:
arch/riscv/cpu/mtrap.S: Assembler messages:
arch/riscv/cpu/mtrap.S:65: Error: unrecognized opcode `csrr a0,scause'
arch/riscv/cpu/mtrap.S:66: Error: unrecognized opcode `csrr a1,sepc'
arch/riscv/cpu/mtrap.S:67: Error: unrecognized opcode `csrr a2,stval'
arch/riscv/cpu/mtrap.S:70: Error: unrecognized opcode `csrw sepc,a0'
Signed-off-by: Alexandre Ghiti <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
Tested-by: Heinrich Schuchardt <[email protected]>
Tested-by: Heiko Stuebner <[email protected]>
Tested-by: Christian Stewart <[email protected]>
Reviewed-by: Rick Chen <[email protected]>
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RISC-V has two code models, medium low (medlow) and medium any (medany).
Medlow limits addressable memory to a single 2 GiB range between the
absolute addresses -2 GiB and +2 GiB. Medany limits addressable memory
to any single 2 GiB address range.
By default, medlow is selected for U-Boot on both 32-bit and 64-bit
systems.
The -mcmodel compiler flag is selected according to the Kconfig
configuration.
Signed-off-by: Lukas Auer <[email protected]>
[bmeng: adjust to make medlow the default code model for U-Boot]
Signed-off-by: Bin Meng <[email protected]>
Reviewed-by: Anup Patel <[email protected]>
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Use the new Kconfig entries to construct the ISA string for the -march
compiler flag. The -mabi compiler flag is selected based on the base
integer instruction set.
With this change, the C (compressed instructions) ISA extension is now
enabled for all boards with CONFIG_RISCV_ISA_C set. Buildman reports a
decrease in binary size of 71590 bytes.
Signed-off-by: Lukas Auer <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
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Currently start.S is inside arch/riscv/cpu/ax25/, but it can be
common for all RISC-V targets.
Signed-off-by: Bin Meng <[email protected]>
Reviewed-by: Lukas Auer <[email protected]>
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This adds a helper routine to print CPU information. Currently
it prints all the instruction set extensions that the processor
core supports.
Signed-off-by: Bin Meng <[email protected]>
Reviewed-by: Lukas Auer <[email protected]>
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When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from. So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry. Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.
In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.
This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents. There's also a few places where I found we did not have a tag
and have introduced one.
Signed-off-by: Tom Rini <[email protected]>
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Add Kconfig and makefile for RISC-V
Also modify MAINTAINERS for it.
Signed-off-by: Rick Chen <[email protected]>
Signed-off-by: Rick Chen <[email protected]>
Signed-off-by: Greentime Hu <[email protected]>
Cc: Padmarao Begari <[email protected]>
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