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| author | Miguel Ojeda <ojeda@kernel.org> | 2026-08-16 15:32:33 +0200 |
|---|---|---|
| committer | Miguel Ojeda <ojeda@kernel.org> | 2026-08-23 21:27:17 +0200 |
| commit | 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 (patch) | |
| tree | 93a1ed1d337bc53adf1e572c2586d347703b286e /Documentation/PCI/controller | |
| download | linux-stable-5febf432df1cfa5b25d99b54c32103fafbdd0eb9.tar.gz linux-stable-5febf432df1cfa5b25d99b54c32103fafbdd0eb9.zip | |
kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted
Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:
vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd
The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.
This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.
Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.
Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'Documentation/PCI/controller')
| -rw-r--r-- | Documentation/PCI/controller/index.rst | 10 | ||||
| -rw-r--r-- | Documentation/PCI/controller/rcar-pcie-firmware.rst | 32 |
2 files changed, 42 insertions, 0 deletions
diff --git a/Documentation/PCI/controller/index.rst b/Documentation/PCI/controller/index.rst new file mode 100644 index 000000000..c2ce9ccdc --- /dev/null +++ b/Documentation/PCI/controller/index.rst @@ -0,0 +1,10 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=========================================== +PCI Native Host Bridge and Endpoint Drivers +=========================================== + +.. toctree:: + :maxdepth: 2 + + rcar-pcie-firmware diff --git a/Documentation/PCI/controller/rcar-pcie-firmware.rst b/Documentation/PCI/controller/rcar-pcie-firmware.rst new file mode 100644 index 000000000..67d3bf66e --- /dev/null +++ b/Documentation/PCI/controller/rcar-pcie-firmware.rst @@ -0,0 +1,32 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================================================= +Firmware of PCIe controller for Renesas R-Car V4H +================================================= + +Renesas R-Car V4H (r8a779g0) has a PCIe controller, requiring a specific +firmware download during startup. + +However, Renesas currently cannot distribute the firmware free of charge. + +The firmware file "104_PCIe_fw_addr_data_ver1.05.txt" (note that the file name +might be different between different datasheet revisions) can be found in the +datasheet encoded as text, and as such, the file's content must be converted +back to binary form. This can be achieved using the following example script: + +.. code-block:: sh + + $ awk '/^\s*0x[0-9A-Fa-f]{4}\s+0x[0-9A-Fa-f]{4}/ { print substr($2,5,2) substr($2,3,2) }' \ + 104_PCIe_fw_addr_data_ver1.05.txt | \ + xxd -p -r > rcar_gen4_pcie.bin + +Once the text content has been converted into a binary firmware file, verify +its checksum as follows: + +.. code-block:: sh + + $ sha1sum rcar_gen4_pcie.bin + 1d0bd4b189b4eb009f5d564b1f93a79112994945 rcar_gen4_pcie.bin + +The resulting binary file called "rcar_gen4_pcie.bin" should be placed in the +"/lib/firmware" directory before the driver runs. |