patch notes · #307 October

#30 · The install keeps only the chain that runs: about 0.25 GB on disk instead of 1.5

What a clean install left behind. The install line said # ~4 min, 1.4 GB, once, and a clean install into an empty folder measured on 7 October was 1543 MB with 25 .git folders in it: nextpnr-xilinx 1086 MB (its full prjxray-db submodule holds five FPGA families, 853 MB, the Basys3 reads one), prjxray 217 MB (ten submodules, four never built), yosys-slang 101 MB of sources around a 9 MB plugin, and every build tree. The chain that runs, the binary, the artix7 database, the chip database, the venv, fasm2frames, xc7frames2bit and slang.so, is 237 MB. The installer asked for 4 GB free: the install needs 1.4 GB plus build scratch, at least 4 GB.

Now the install fetches less and removes what it built from. nextpnr-xilinx comes with the two submodules its chip-database exporter reads, prjxray-db as a partial clone of artix7 alone; prjxray with the six submodules its cmake uses; the four it never builds (fasm, yosys, python-sdf-timing, display_port, 100 MB) are not fetched. After each build the sources and the build tree go, and the installer says what stays: ✓ prjxray pruned to xc7frames2bit, utils/ and the python package (2 MB), ✓ nextpnr-xilinx pruned to the binary and the artix7 database (86 MB), ✓ slang.so built, loads in Yosys 0.69+post (read_slang); sources removed (9 MB kept). Every step header carries the size so far ([6] yosys-slang (SystemVerilog reader plugin, from source, ~3 min) (+218s, 246 MB)), the last line is Total: 415 s, ~/fpga: 255 MB., and the free-space check now asks for 2 GB: the build peaks at about 850 MB (the install that stays is ~237 MB), so at least 2 GB are needed. (the peak printed by the three clean installs of 7 October: 811, 833 and 834 MB, at the chip database step, when the sources, the build trees and the 268 MB .bba are all there at once). A second run skips every step by its stamp and the files it left, no git involved: ↷ nextpnr-xilinx @ 3fd7878 (binary + artix7 database) (already there, skipped), `↷ prjxray @ c9f02d8 (xc7frames2bit

fasm2frames) (already there, skipped), ↷ slang.so @ 9676786 (built for Yosys 0.69+post) (already there, skipped), Total: 3 s. A chip database that went missing with the sources already pruned fetches and builds nextpnr-xilinx again, and prunes it again. An install interrupted during a build (Ctrl-C, sleep, a compiler error) is resumed by the next run with the checkout still there, and that run prunes it like a first run would (found by the independent review: the first version only pruned what the same run had fetched, so an interrupted install kept 637 MB and three .gitfor good). Aslang.so built by hand with the manual's lines, which never write the installer's commit stamp, is load-tested, stamped and pinned instead of being cloned and compiled again (130 MB, 3 minutes); a hand checkout at another commit is named (the checkout at ~/fpga/yosys-slang is at , not the pinned 9676786) and the pinned plugin is built next to it. A Yosys upgrade still rebuilds the plugin in a side folder and replaces slang.so only once Yosys loads the new one. The manual's new section 3.7 lists what a by-hand chain can delete to land at the same size. The pages say the measured number (about 0.3 GB on disk, 237 MB measured on 7 October), and that an install made before 7 October keeps its 1.5 GB until dewfpga uninstall && dewfpga install`.

Numbers. Clean install into an empty folder: 1543 MB → 237 MB in the closing run's second full run (the suite's du right after the install, log included; the first full run's du said 253 MB, and the integrator's install of the same morning measures 237 MB), .git folders 25 → 0, 415 s for the install, 3 s for the second run. The Homebrew side, which the pages' number never included, measured on this Mac: the eight packages the installer asks for are 237 MB (python@3.14 87, cmake 71, yosys 50, eigen 11, openFPGALoader 10, Icarus Verilog 7, ninja and pkg-config under 1), and the 16 packages they pull in another 562 MB (boost 377, icu4c 84, tcl-tk 43, openssl 39). So a student's Mac gets about 0.25 GB in ~/fpga and about 0.8 GB under Homebrew, plus the 51 MB agent SDK if they ask for it. The compiler did not change: the probe table of the closing run is byte-identical to #28-#29's (synthesis 108/133, all four stages 95/133, Vivado-supported probes passing all four stages 86/111, known gaps 25), and the fresh chain's blink .fasm equals the golden one.

Tests. Four new checks in the FULL=1 section (listed checks 343 → 347): the clean install is under 1 GB (its MB printed under the PASS line), it leaves no .git at any depth, a second run skips every step in under 10 s with no built line, and uninstall removes the fresh folder whole. The size checks were run by the update's builder against the installer from before this update and fail there (1543 MB, 25 clones); against the new one they pass. The suite now also puts the tree's .fpga_home back after the clean install, which the install's step 7 overwrites. shellcheck -S style and bash -n on the new install.sh are clean. Not exercised end to end: the rebuild after a Yosys upgrade (same code path as the clean build, with the pruning after it) and a venv rebuilt after a Homebrew Python upgrade (prjxray keeps setup.py and README.md for that pip install -e).

Closing run (7 October, board unplugged). The first run: passed 319, failed 1, known gaps 25, and the one FAIL was not the product: no personal paths found templates/__pycache__/mcp_setup.cpython-314.pyc, left at 04:41 by a run of the MCP test without -B (its rollback test imports mcp_setup.py), carrying this Mac's home path, the same class of leftover #7's closing run hit. The test now sets sys.dont_write_bytecode like its two sibling suites, so a run without -B leaves nothing. The second run: passed 320, failed 0, known gaps 25, one PASS more than the first (the fixed check), its probe table byte-identical to the first run's and to #28-#29's. The clean install took 415 s in the first run (peak 811 MB) and printed a peak of 810 MB in the second; its second run took 3 s both times, and find -name .git over the live fresh folder the moment its last build ended found nothing (89 MB chipdb, 86 nextpnr-xilinx, 52 venv, 9 yosys-slang, 2 prjxray, 1 install.log: 237 MB). The clean install's du is the number above. The board check: SKIP flash on the board: no board (no FTDI device on the USB bus during either run). Mail suites: 9 suites, each exit 0 (activation SQL 142, SQL 187, mail flow 60, sender idempotency, lifecycle 112, usage 13, integration 8, pages 139, Chromium and WebKit 158; 0 failures). Site check: 112 pages, 2055 links, 0 failures.

Open.

An install from before 7 October keeps its clones (1.5 GB); the installer leaves it as it is, and the pages say the two commands that get the small one.
The 51 MB for the optional agent SDK is the figure from before this update, not re-measured today (no mcp-venv on this Mac's ~/fpga).
The .bit of two installs differs by 2 bytes, the timestamp in its header; the frames are identical.
On the skip path the installer trusts the stamps and does not load slang.so into Yosys again (dewfpga check does, every time it runs); a new pinned commit or a new yosys -V line still rebuilds.
The rebuild's sources go to ~/fpga/yosys-slang/src.new, inside the folder uninstall removes, so a rebuild that failed leaves nothing uninstall would miss.
Every install.sh run links Homebrew's bin/dewfpga to the CLI that ran it and writes that tree's .fpga_home; the suite restores .fpga_home, the link is restored by hand after a run from a checkout.
The three pruned checkouts' .git sat at depth 2, 4 and 4; the no-clone check looked two levels deep when the review read it and now looks at every depth (verified with find on both installs of 7 October: 0 and 25).

previous: #29 A failed build leaves no old bitstream, wrong pins are named, a quick save rebuilds
next: #31 A random-design generator checks the SystemVerilog DDCA teaches against its own simulation
This entry in the full list
The commands this entry names: dewfpga install · dewfpga check · dewfpga uninstall · dewfpga mcp
Every SystemVerilog construct measured so far, next to what Vivado does: the probes, stage by stage