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A new kgdb feature will soon land (kgdb_earlycon) that lets us run kgdb much earlier. In order for everything to work properly it's important that the break hook is setup by the time we process "kgdbwait". Right now the break hook is setup in debug_traps_init() and that's called from arch_initcall(). That's a bit too late since kgdb_earlycon really needs things to be setup by the time the system calls dbg_late_init(). We could fix this by adding call_break_hook() into early_brk64() and that works fine. However, it's a little ugly. Instead, let's just add a call to debug_traps_init() straight from trap_init(). There's already a documented dependency between trap_init() and debug_traps_init() and this makes the dependency more obvious rather than just relying on a comment. NOTE: this solution isn't early enough to let us select the "ARCH_HAS_EARLY_DEBUG" KConfig option that is introduced by the kgdb_earlycon patch series. That would only be set if we could do breakpoints when early params are parsed. This patch only enables "late early" breakpoints, AKA breakpoints when dbg_late_init() is called. It's expected that this should be fine for most people. It should also be noted that if you crash you can still end up in kgdb earlier than debug_traps_init(). Since you don't need breakpoints to debug a crash that's fine. Suggested-by: Will Deacon <will@kernel.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Acked-by: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20200513160501.1.I0b5edf030cc6ebef6ab4829f8867cdaea42485d8@changeid Signed-off-by: Will Deacon <will@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.