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opentitan: Makefile: Use riscv64-elf-objcopy to prepare images #2104

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merged 1 commit into from Sep 17, 2020
Merged

opentitan: Makefile: Use riscv64-elf-objcopy to prepare images #2104

merged 1 commit into from Sep 17, 2020

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alistair23
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Pull Request Overview

Call the riscv64-elf-objcopy binary to create binaries.

The LLVM objcopy doesn't correctly create working binaries. So let's
avoid calling it. At the same time the riscv64 will correctly work and
is more likely to be installed so let's use it instead.

Testing Strategy

Running the Makefile to flash images to the OT FPGA.

TODO or Help Wanted

Documentation Updated

  • Updated the relevant files in /docs, or no updates are required.

Formatting

  • Ran make prepush.

@alistair23
opentitan: Makefile: Use riscv64-elf-objcopy to prepare images
6f3deb6 
Call the riscv64-elf-objcopy binary to create binaries.

The LLVM objcopy doesn't correctly create working binaries. So let's
avoid calling it. At the same time the riscv64 will correctly work and
is more likely to be installed so let's use it instead.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
bradjc
bradjc requested changes Sep 11, 2020
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Can we dig into why? Conceptually what is happening is pretty simple. And, we have seen how painful it can be to install riscv64-gcc, which is why using the rust provided tools is so convenient.

@alistair23
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I have no idea and I don't have a good way to figure out. It's just a binary blob. One boots on OT and one doesn't.

@ppannuto
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Maybe worth pinging the LLVM devs? They've been responsive to issues like this before, seems they aspire to parity in tooling where sensible / possible, and this is probably a bug there.

@bradjc bradjc added the WG-OpenTitan In the purview of the OpenTitan working group. label Sep 17, 2020
@alistair23
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I filed a bug, let's see what happens: https://bugs.llvm.org/show_bug.cgi?id=47563

@hudson-ayers
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@alistair23 does riscv32-none-elf-objcopy not work if used in both positions?

Given that this rule already requires a risc-v specific objcopy because llvm objcopy does not support --update-section, it seems like it might be worth merging this to fix master, especially if we can keep it so we only require the objcopy that people had to use previously.

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@hudson-ayers Do you mean llvm-objcopy?

We can't use llvm-objcopy for the first objcopy as it doesn't support --update-sections.

Most machines don't use riscv32-none-elf-objcopy but instead use riscv64-elf-objcopy hence the change to it. Both are GCC tools though. riscv32-none-elf-objcopy came from my OE toolchain, most users will just use riscv64-elf-objcopy.

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@hudson-ayers Do you mean llvm-objcopy?

We can't use llvm-objcopy for the first objcopy as it doesn't support --update-sections.

Most machines don't use riscv32-none-elf-objcopy but instead use riscv64-elf-objcopy hence the change to it. Both are GCC tools though. riscv32-none-elf-objcopy came from my OE toolchain, most users will just use riscv64-elf-objcopy.

I meant riscv32-none-elf-objcopy just because that is what was there previously. But that makes sense, I think it is reasonable to merge this because a non-llvm objcopy is required for this make rule anyway.

@bradjc bradjc merged commit cb748be into tock:master Sep 17, 2020
@alistair23 alistair23 deleted the alistair/opentitan-makefile branch September 17, 2020 20:41
@jwnrt jwnrt mentioned this pull request Mar 8, 2023
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bors bot added a commit that referenced this pull request Apr 19, 2023
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Merge #3411
0503b8d 
3411: Update OpenTitan Makefile and build examples  r=hudson-ayers a=jwnrt

## Pull Request Overview

This pull updates parts of OpenTitan's Makefile and README that I ran into when trying to build and run Tock:

## Disable default board configuration

Disabled the default `fpga_cw310` Cargo feature when a `BOARD_CONFIGURATION` is specified.

Previously, both `fpga_cw310` and `sim_verilator` would be set, leading to conflicting `const CONFIG` definitions in `chips/earlgrey`.

### Objcopy binary

The Makefile is using `riscv64-linux-gnu-objcopy` as documented in #2104. The reasoning was that `llvm-objcopy` wasn't providing correct output.

From #2104 it looks like `riscv64-linux-gnu` was chosen because users were likely to have it installed. `riscv32-unknown-elf-objcopy` is provided by the lowRISC toolchain used for building OpenTitan software, so I thought developers would be more likely to have this already installed.

Happy not to include this change, though. I also haven't checked whether the `llvm-objcopy` bug is now resolved and that could be used instead.

### README examples

The QEMU examples in the README were outdated, possibly since `libtock-rs` has updated. Updated these examples, and tidied up some Markdown along the way.

## Testing Strategy

This pull request was tested by running the updated README examples and make rules.

## TODO or Help Wanted

Any thoughts on using `riscv32-unknown-elf-objcopy` by default over `riscv64-linux-gnu`?

## Documentation Updated

- [x] Updated the relevant files in `/docs`, or no updates are required.
- [x] Updated example commands in OpenTitan's README

## Formatting

- [x] Ran `make prepush`.

Co-authored-by: James Wainwright <james.wainwright@lowrisc.org>
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@bradjc bradjc bradjc approved these changes

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@alistair23 @ppannuto @hudson-ayers @bradjc