Further optimization for space (-Os -> -Oz): musl-cross-make-> bump to gcc 15.1.0 & related changes

[tlaurion]

• MERGE Add CBFS/IFD validation + CBFS free space for coreboot builds #2041 first!
• test oem factory reset + tpm duk + kexec on nv4x_adl
• build is reproducible

---

• bumps musl-cross-make to latest commit, bump gcc 9.4.0 -> 15.1.0; rename/bump kexec-tools to latest version (2.0.32) + gcc 15.1.0, switch/patch modules to switch from -Os to -Oz

Stats diff since #2041 got merged for x220-hotp-maximized

Master

As can be seen on CircleCI x220-hotp-maximized build :

Jan 06 22:44:08 "/root/heads/build/x86/coreboot-25.09/EOL_t420-hotp-maximized/cbfstool" "/root/heads/build/x86/coreboot-25.09/EOL_t420-hotp-maximized/coreboot.rom" print
Jan 06 22:44:08 FMAP REGION: COREBOOT
Jan 06 22:44:08 Name                           Offset     Type           Size   Comp
Jan 06 22:44:08 cbfs_master_header             0x0        cbfs header        32 none
Jan 06 22:44:08 cpu_microcode_blob.bin         0x80       microcode       26624 none
Jan 06 22:44:08 fallback/romstage              0x68c0     stage          101016 none
Jan 06 22:44:08 fallback/ramstage              0x1f3c0    stage          151125 LZMA (323316 decompressed)
Jan 06 22:44:08 config                         0x44280    raw              3526 LZMA (11252 decompressed)
Jan 06 22:44:08 revision                       0x45080    raw               766 none
Jan 06 22:44:08 build_info                     0x453c0    raw               101 none
Jan 06 22:44:08 bootsplash.jpg                 0x45480    bootsplash      43282 none
Jan 06 22:44:08 fallback/dsdt.aml              0x4fdc0    raw             14520 none
Jan 06 22:44:08 vbt.bin                        0x536c0    raw              1368 LZMA (3985 decompressed)
Jan 06 22:44:08 cmos.default                   0x53c80    cmos_default      256 none
Jan 06 22:44:08 cmos_layout.bin                0x53dc0    cmos_layout      2120 none
Jan 06 22:44:08 fallback/postcar               0x54640    stage           31180 none
Jan 06 22:44:08 fallback/payload               0x5c080    simple elf    7714640 none
Jan 06 22:44:08 (empty)                        0x7b7800   null            71076 none
Jan 06 22:44:08 bootblock                      0x7c8dc0   bootblock       28672 none
Jan 06 22:44:08 
Jan 06 22:44:08 Validating final CBFS/IFD configuration...
Jan 06 22:44:08 ===================================================================
Jan 06 22:44:08 IFD vs CBFS Size Validation
Jan 06 22:44:08 ===================================================================
Jan 06 22:44:08 IFD BIOS Region: 0x00018000 - 0x007fffff
Jan 06 22:44:08 IFD BIOS Size:   0x7E8000 (8096 KiB)
Jan 06 22:44:08 CONFIG_CBFS_SIZE: 0x7E7FFF (8095 KiB)
Jan 06 22:44:08 
Jan 06 22:44:08 ✓ CONFIG_CBFS_SIZE fits within IFD BIOS region
Jan 06 22:44:08    Unused IFD capacity: 1 bytes (< 1 KiB)
Jan 06 22:44:08 
Jan 06 22:44:08 CBFS Free Space: 71076 bytes (69 KiB)
Jan 06 22:44:08 
Jan 06 22:44:08 ===================================================================
Jan 06 22:44:08 ✓ Validation complete
Jan 06 22:44:08 ===================================================================

This PR

"/home/user/heads/build/x86/coreboot-25.09/EOL_x220-hotp-maximized/cbfstool" "/home/user/heads/build/x86/coreboot-25.09/EOL_x220-hotp-maximized/coreboot.rom" print
FMAP REGION: COREBOOT
Name                           Offset     Type           Size   Comp
cbfs_master_header             0x0        cbfs header        32 none
cpu_microcode_blob.bin         0x80       microcode       26624 none
fallback/romstage              0x68c0     stage           99128 none
fallback/ramstage              0x1ec80    stage          148459 LZMA (316668 decompressed)
config                         0x430c0    raw              3558 LZMA (11286 decompressed)
revision                       0x43f00    raw               772 none
build_info                     0x44240    raw               101 none
bootsplash.jpg                 0x44300    bootsplash      43282 none
fallback/dsdt.aml              0x4ec40    raw             14520 none
vbt.bin                        0x52540    raw              1400 LZMA (3985 decompressed)
cmos_layout.bin                0x52b00    cmos_layout      1976 none
fallback/postcar               0x53300    stage           30564 none
fallback/payload               0x5aac0    simple elf    7573984 none
(empty)                        0x793d00   null           217252 none
bootblock                      0x7c8dc0   bootblock       28672 none

Validating final CBFS/IFD configuration...
===================================================================
IFD vs CBFS Size Validation
===================================================================
IFD BIOS Region: 0x00018000 - 0x007fffff
IFD BIOS Size:   0x7E8000 (8096 KiB)
CONFIG_CBFS_SIZE: 0x7E7FFF (8095 KiB)

✓ CONFIG_CBFS_SIZE fits within IFD BIOS region
   Unused IFD capacity: 1 bytes (< 1 KiB)

CBFS Free Space: 217252 bytes (212 KiB)

===================================================================
✓ Validation complete
===================================================================

Gain of 212 - 69 = 143 KiB free for most constrained board

Continues #590

[tlaurion]

This PR will be needed soon, since xx20 (t420/x220) are near space exhaustion (less than 100kb free left) as can be seen at #2041 (comment) : the t420-hotp-maximized rom has 67kb free left in CBFS region.

[tlaurion]

https://app.circleci.com/pipelines/github/tlaurion/heads/3449/workflows/6b0bd1cc-8d3f-43f4-b176-1c4f6435a36b/jobs/76833/parallel-runs/0/steps/0-102?invite=true#step-102-2244532_182

2d073289ba2bb5ba6be6650c055928faf8020931f61eeb35c1b3bfe3625f55b8 /root/heads/build/x86/EOL_x220-hotp-maximized/heads-EOL_x220-hotp-maximized-v0.2.0-2902-g6b403e0.rom

Local build:

2d073289ba2bb5ba6be6650c055928faf8020931f61eeb35c1b3bfe3625f55b8 /home/user/heads/build/x86/EOL_x220-hotp-maximized/heads-EOL_x220-hotp-maximized-v0.2.0-2902-g6b403e0.rom

Builds are reproducible if built clean (./docker_repro.sh make BOARD=xyz real.clean && make BOARD=xyz )

[Copilot]

Pull request overview

This PR upgrades the Heads build toolchain from GCC 9.4.0 to GCC 15.1.0 and systematically switches compiler optimization flags from -Os (optimize for size) to -Oz (optimize aggressively for size) across 30+ modules. The changes deliver a 1.44% space reduction (115 KB) in the final firmware payload through improved compiler optimization and enhanced binary stripping.

Key changes include:

• GCC toolchain upgrade via musl-cross-make bump to latest commit with GCC 15.1.0
• C23 compatibility patches for multiple modules (tpmtotp, powerpc-utils, bash, e2fsprogs, gpg2, cairo, linux kernel)
• Systematic -Os to -Oz optimization flag conversion across all modules
• New CBFS/IFD validation script with automatic size fixing capability
• Module version bumps: kexec-tools (2.0.26→2.0.31), dropbear (2016.74→2025.88)
• Enhanced Makefile with GPG injection caching and improved stripping flags
• Disabled features in OpenSSL and LVM2 for additional space savings

Reviewed changes

Copilot reviewed 59 out of 60 changed files in this pull request and generated 13 comments.

Show a summary per file

File	Description
modules/musl-cross-make	Bumps commit hash and GCC version from 9.4.0 to 15.1.0 with upgrade notes
patches/musl-cross-make-3635262e4524c991552789af6f36211a335a77b3/0001-use-gcc-15_1_0.patch	Updates musl-cross-make Makefile to use GCC 15.1.0
patches/tpmtotp-4d63d21c8b7db2e92ddb393057f168aead147f47/*.patch	Three patches fixing GCC 15.1.0 compatibility issues (function signatures, printf formats, AES macro)
patches/powerpc-utils-1.3.5/0001-fix-rtas-function-pointer-signatures-gcc15.patch	Fixes function pointer declarations for C23 compatibility
patches/kexec-tools-2.0.31/*.patch	Six patches for kexec-tools 2.0.31: disables unused modules, improves framebuffer support, adds EBDA workaround, fixes purgatory build, uses build compiler for utils, adds x86-64 baseline flags
patches/lvm2-2.03.23.patch	Adds libgen.h include for basename() function required by GCC 15.1.0
patches/linux-6.6.16-openpower/0008-powerpc-boot-Fix-C23-bool-compatibility-for-GCC-15.patch	Adds -std=gnu11 to PowerPC boot Makefile for C23 bool keyword conflicts
patches/dropbear-2025.88/0001-disable-fatal-user-group-change-errors-for-heads-environment.patch	Updates patch paths for dropbear 2025.88 source tree restructuring
patches/coreboot-talos_2/0003-ugly_skiboot-patch_fix_for_newer_gcc_from_musl_125.patch	Adds additional GCC 15.1.0 warning suppressions for skiboot (-Wno-error=unterminated-string-initialization, -Wno-error=misleading-indentation)
patches/bash-5.1.16.patch	Adds unistd.h include to lib/termcap/tparam.c for write() declaration
modules/kexec	Deleted - replaced by modules/kexec-tools
modules/kexec-tools	New module file for kexec-tools 2.0.31 with -Oz optimization
modules/dropbear	Updates to version 2025.88 with additional configure options for space savings
modules/openssl	Switches to -Oz and disables additional protocols/algorithms (dtls, ec2m, engine, gost, md2, srp, ssl3, tls1, tls1_1)
modules/lvm2	Switches to -Oz and disables advanced features (thin, cache, VDO, writecache, integrity, snapshots, mirrors)
modules/linux	Adds -std=gnu11 flag and PowerPC-specific GCC 15.1.0 compatibility flags
modules/bash	Changes to -Oz with -std=gnu11 for C23 compatibility
modules/cairo	Changes to -Oz with -std=gnu11, -Wno-inline, -Wno-incompatible-pointer-types
modules/coreboot	Adds validation script calls and extensive GCC 15.1.0 compatibility documentation
modules/e2fsprogs	Changes to -Oz with -std=gnu11 for C23 bool keyword conflicts
modules/gpg2	Changes to -Oz with -std=gnu11 and adds -DDISABLE_PHOTO_VIEWER
modules/libgcrypt	Changes to -Oz and disables jent-support
modules/zstd, modules/util-linux, modules/tpmtotp, modules/qrencode, modules/powerpc-utils, modules/pixman, modules/pinentry, modules/newt, modules/ncurses, modules/mbedtls, modules/libusb-compat, modules/libusb, modules/libpng, modules/libnitrokey, modules/libksba, modules/libhidapi-libusb, modules/libgpg-error, modules/libassuan, modules/kbd, modules/ioport, modules/io386, modules/gpg, modules/flashtools, modules/flashrom, modules/flashprog, modules/fbwhiptail, modules/exfatprogs, modules/cryptsetup2, modules/cryptsetup	All changed from -Os to -Oz optimization
bin/validate_cbfs_ifd_fit.sh	New validation script that checks CONFIG_CBFS_SIZE against IFD BIOS region with auto-fix capability
Makefile	Adds validation targets, enhances strip flags (--strip-all), implements GPG injection caching, adds verbose build hints, fixes kexec module reference, adds coreboot cbmem GCC 15.1.0 compatibility flag

Comments suppressed due to low confidence (2)

patches/dropbear-2025.88/0001-disable-fatal-user-group-change-errors-for-heads-environment.patch:1

• The patch header line references the old path "dropbear-2016.74" but this module is being updated to "dropbear-2025.88". The patch should use paths that match the new version to avoid confusion during patch application.
  patches/dropbear-2025.88/0001-disable-fatal-user-group-change-errors-for-heads-environment.patch:12
• Commenting out the dropbear_exit calls when setgid/initgroups or setuid fail means the server will continue executing the user session even if it could not drop privileges to ses.authstate.pw_uid/pw_gid, so a user who authenticated as an unprivileged account could end up with a shell running under the original (likely root) UID/GID. This silently bypasses the operating system’s privilege separation mechanisms and can turn any failure in the privilege-dropping path (for example due to security policy or environment issues) into a remote privilege escalation to the Dropbear daemon’s UID. The fix is to keep these failures fatal (e.g., by retaining dropbear_exit or otherwise aborting the session) so that no user commands are executed when user/group changes fail.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.