Date: Tue, 22 Sep 2015 21:59:48 -0700 From: Rui Paulo <rpaulo@me.com> To: Ed Maste <emaste@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: HEADS UP: Standalone kernel debug files moving out of /boot/kernel (really, this time) Message-ID: <1442984388.24327.23.camel@me.com> In-Reply-To: <CAPyFy2BVqrKK2nWF9%2BJ6U6iGvmBkfb5%2BCN6bN-5tz7MUGEUy8Q@mail.gmail.com> References: <CAPyFy2BVqrKK2nWF9%2BJ6U6iGvmBkfb5%2BCN6bN-5tz7MUGEUy8Q@mail.gmail.com>
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On Tue, 2015-09-22 at 10:23 -0400, Ed Maste wrote: > I am preparing to move the standalone kernel debug data out of > /boot/kernel/ into /usr/lib/debug/boot/kernel/, mirroring the > approach > used for userland debug data. This significantly reduces the boot > partition size requirement, and is a step towards supporting the > installation of kernel debug data ony when required. LLDB and GDB > automatically search for debug data under /usr/lib/debug/ so this > change should be transparent from an end-user perspective. > > The change can be reviewed in Phabricator at > https://reviews.freebsd.org/D1006 and can be fetched as a unified > diff > from https://people.freebsd.org/~emaste/patches/D1006.diff > > This change was discussed on -current last year[1] and a number of > concerns were raised. These are addressed in the updated patch, and > I'll summarize them here: > > * /usr/lib seems like an odd location for this data > /usr/lib/debug is the standard location established by GDB, and seems > reasonable enough. I don't want to introduce gratuitous differences > when compared with other systems. > > * Do gdb / lldb look also in /usr/local/lib/debug, for ports debug > files? > Not yet; this is definitely something to address with additional > work. > > * Is it possible to keep the current behaviour? > Yes, set KERN_DEBUGDIR="" in src.conf(5). > > * /usr now needs to be mounted for savecore to work > Savecore does not rely on debug files; crashinfo does. As crashinfo > also requires /usr/bin/gdb /usr already needs to be mounted. > > * This makes working with multiple kernels more difficult. > Users with a workflow requiring a single "cp" or "mv" to shuffle > around kernels and debug data can use the src.conf(5) setting to keep > things as today. The techniques documented in build(7) for working > with multiple named kernels require no changes; for example a kernel > in /boot/newkernel/ will have its debug data in > /usr/lib/debug/boot/newkernel/. The kernel to kernel.old rotation > also > works on both /boot/kernel and /usr/lib/debug/boot/kernel. > > * Why rename .symbols to .debug? > 1) This is what they're called elsewhere. > 2) It's not an accurate description of the file's content. Some > symbol > data also exists in the binary or library, and there is a lot more > debugging information in the standalone debug file than just symbols. > 3) Userland and kernel debug data will have the same debug extension. > Renaming them along with the other changes is a better approach than > having another change later on. > > I plan to commit the change later this week. > Yay, thanks! -- Rui Paulo
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