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2016-02-22cbfs: Add LZ4 in-place decompression support for pre-RAM stagesJulius Werner
This patch ports the LZ4 decompression code that debuted in libpayload last year to coreboot for use in CBFS stages (upgrading the base algorithm to LZ4's dev branch to access the new in-place decompression checks). This is especially useful for pre-RAM stages in constrained SRAM-based systems, which previously could not be compressed due to the size requirements of the LZMA scratchpad and bounce buffer. The LZ4 algorithm offers a very lean decompressor function and in-place decompression support to achieve roughly the same boot speed gains (trading compression ratio for decompression time) with nearly no memory overhead. For now we only activate it for the stages that had previously not been compressed at all on non-XIP (read: non-x86) boards. In the future we may also consider replacing LZMA completely for certain boards, since which algorithm wins out on boot speed depends on board-specific parameters (architecture, processor speed, SPI transfer rate, etc.). BRANCH=None BUG=None TEST=Built and booted Oak, Jerry, Nyan and Falco. Measured boot time on Oak to be about ~20ms faster (cutting load times for affected stages almost in half). Change-Id: Iec256c0e6d585d1b69985461939884a54e3ab900 Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/13638 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin <adurbin@chromium.org>
2015-07-21libpayload: lz4: Add output overrun check to incompressible caseJulius Werner
The LZ4 decompressor currently doesn't check for output overruns before writing data in the case where a block had been incompressible (and included verbatim in the compression stream). This is extremely unlikely with the default 4MB blocks, but still a nice thing to fix. We'll still output as much data as we can before returning an error to support partial decompression use cases. This matches the behavior already in place for normal, LZ4-compressed blocks where the decompression function is already (supposed to be) doing complete bounds checking (although it is not guaranteed to output all valid bytes before aborting on an output overrun, and you should try to provide a few dozen bytes of extra buffer space beyond the parts you're interested in on partial decompression). BRANCH=None BUG=chrome-os-partner:32184 TEST=None Change-Id: I5e40c8cec8947ec0ec8f6d8c8fa2574cfb4dc958 Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: 636985334c9b3b93a12d4066d2829f1f999c9315 Original-Change-Id: Iecf44650aade60b9fa1b13e57da752fb482a3f3f Original-Signed-off-by: Julius Werner <jwerner@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/286240 Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: http://review.coreboot.org/11016 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org> Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
2015-07-09libpayload: Add LZ4 decompression algorithmJulius Werner
This patch adds support for the LZ4 decompression algorithm to libpayload. It's what all the cool kids are using for decompression these days and has many interesting advantages over LZMA (and everything else I know of): blazing fast decompression (20(!) times faster than LZMA, twice as fast as LZO on my Cortex-A72), no memory requirements on decompression, and possibly in-place decompression support. It pays for that with a lower compression ratio (about 50% larger compressed size than LZMA, 10% larger than LZO for an ARM64 Linux kernel binary), but the boot time math still works in its favor for our IO speeds. This patch only adds the raw decompression functions for use by external payloads, we can later try integrating them in CBFS. It copies the decompression code itself unmodified from the upstream LZ4 library at github.com/Cyan4973/lz4 which will hopefully make it easy to update. The frame format parsing is reimplemented since the upstream version looks unnecessarily complex and unreadable for our needs. BRANCH=smaug BUG=chrome-os-partner:32184 TEST=With other patches, booted ARM64 kernel that got compressed from 15M to 5.1M and decompresses in 44ms. Change-Id: I65bdc4b2b19bd51c7b7e17a4e4b79da301a2a014 Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: f8a1fc996d5b0234d07f567fa8163d0f802d5144 Original-Change-Id: I15c0620da05561ade2552b15ffdf6bb3afd7eb26 Original-Signed-off-by: Julius Werner <jwerner@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/282743 Original-Reviewed-by: Stefan Reinauer <reinauer@google.com> Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: http://review.coreboot.org/10845 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>