GDB 6.1.1 was released in June 2004 and is long obsolete. It does not support all of the architectures that FreeBSD does, and imposes limitations on the FreeBSD kernel build, such as the continued use of DWARF2 debugging information. It was kept (in /usr/libexec/) only for use by crashinfo(8), which extracts some basic information from a kernel core dump after a crash. Crashinfo already prefers gdb from port/package if installed. Future work may add kernel debug support to LLDB or find another path for crashinfo's needs, but in any case we do not want to ship the excessively outdated GDB in FreeBSD 13. Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D27610
The current default is provided in various Makefile.inc in some top-level directories and covers a good portion of the tree, but doesn't cover parts of the build a little deeper (e.g. libcasper). Provide a default in src.sys.mk and set WARNS to it in bsd.sys.mk if that variable is defined. This lets us relatively cleanly provide a default WARNS no matter where you're building in the src tree without breaking things outside of the tree. Crunchgen has been updated as a bootstrap tool to work on this change because it needs r365605 at a minimum to succeed. The cleanup necessary to successfully walk over this change on WITHOUT_CLEAN builds has been added. There is a supplemental project to this to list all of the warnings that are encountered when the environment has WARNS=6 NO_WERROR=yes: https://warns.kevans.dev -- this project will hopefully eventually go away in favor of CI doing a much better job than it. Reviewed by: emaste, brooks, ngie (all earlier version) Reviewed by: emaste, arichardson (depend-cleanup.sh change) Differential Revision: https://reviews.freebsd.org/D26455
This change allows any downstream or otherwise consumer to easily override the new -fno-common default on a temporary basis without having to hack into src.sys.mk, and also makes it a bit easier to search for these specific cases where -fno-common must be overridden with -fcommon or else the build will fail. The gdb build, the only program requiring -fcommon on head/, is switched over as an example usage. It will need it on all branches, so this does not harm future mergability. MFC after: 3 days
In-tree gdb is essentially obsolete. We kept it for sparc64 (because gdb in ports lacked sparc64 support) and as a fallback for crashinfo. gdb was installed to /libexec on all archs other than sparc64, where the WITHOUT_GDB_LIBEXEC option was default, with gdb installed to /usr/bin. With sparc64's retirement WITH_GDB_LIBEXEC became the default for all architectures, but it was still possible to set it off and install gdb into /usr/bin. As the next step in gdb's retirement, remove the option and install gdb only into /libexec as the crashinfo fallback. We expect users to install the gdb port or package for debugging. The in-tree gdb lacks support for a number of supported architectures and does not support contemporary DWARF debug info. Reviewed by: jhb (earlier) Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D24227
As described in the comment, gdb relies on some of the linker magic that happens with -fcommon. I suspect the life expectancy of gdb-in-base is low enough that this isn't worth spending much time addressing, especially given the vintage. Hit it with the -fcommon hammer so that it continues to just work. MFC after: 3 days
location.
itself. This simplifies the upcoming update to newer libedit.
Explicitly specified bare .a libraries need ${PIE_SUFFIX}.
Reported by: David E. Cross, on twitter
Sponsored by: The FreeBSD Foundation
We're studing the possibility of deprecating sbrk(). To make it easier we're removing unnecessicary uses in the base system. None of these tools require sbrk(), but they agressively prefer it for no good reason. Reviewed by: andrew Approved by: re (kib) Sponsored by: DARPA, AFRL Differential Revision: https://reviews.freebsd.org/D16141
The change makes the user and kernel address spaces on i386 independent, giving each almost the full 4G of usable virtual addresses except for one PDE at top used for trampoline and per-CPU trampoline stacks, and system structures that must be always mapped, namely IDT, GDT, common TSS and LDT, and process-private TSS and LDT if allocated. By using 1:1 mapping for the kernel text and data, it appeared possible to eliminate assembler part of the locore.S which bootstraps initial page table and KPTmap. The code is rewritten in C and moved into the pmap_cold(). The comment in vmparam.h explains the KVA layout. There is no PCID mechanism available in protected mode, so each kernel/user switch forth and back completely flushes the TLB, except for the trampoline PTD region. The TLB invalidations for userspace becomes trivial, because IPI handlers switch page tables. On the other hand, context switches no longer need to reload %cr3. copyout(9) was rewritten to use vm_fault_quick_hold(). An issue for new copyout(9) is compatibility with wiring user buffers around sysctl handlers. This explains two kind of locks for copyout ptes and accounting of the vslock() calls. The vm_fault_quick_hold() AKA slow path, is only tried after the 'fast path' failed, which temporary changes mapping to the userspace and copies the data to/from small per-cpu buffer in the trampoline. If a page fault occurs during the copy, it is short-circuit by exception.s to not even reach C code. The change was motivated by the need to implement the Meltdown mitigation, but instead of KPTI the full split is done. The i386 architecture already shows the sizing problems, in particular, it is impossible to link clang and lld with debugging. I expect that the issues due to the virtual address space limits would only exaggerate and the split gives more liveness to the platform. Tested by: pho Discussed with: bde Sponsored by: The FreeBSD Foundation MFC after: 1 month Differential revision: https://reviews.freebsd.org/D14633