From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amerigo Wang Date: Thu, 06 Aug 2009 03:39:23 +0000 Subject: Re: [Patch 0/7] Implement crashkernel=auto Message-Id: <4A7A506B.2060008@redhat.com> List-Id: References: <20090805112123.6552.73574.sendpatchset@localhost.localdomain> <20090805140408.GJ7259@hmsreliant.think-freely.org> <4A7A3A78.7080200@redhat.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Eric W. Biederman" Cc: Neil Horman , linux-kernel@vger.kernel.org, tony.luck@intel.com, linux-ia64@vger.kernel.org, akpm@linux-foundation.org, Ingo Molnar , Anton Vorontsov Eric W. Biederman wrote: > In general I figure that whoever builds the kernel and initrd should be > responsible for testing and figuring out the amount of memory needed. > The primary kernel has no idea what is going to loaded in there and > as such no real idea how much memory is needed. > Yeah, that is exactly why I _didn't_ pick the idea of reserving memory automatically and silently without "crashkernel=auto". If a user specifies "crashkernel=auto", that means he/she has no idea how much memory to be reserved, he/she wants to let the kernel to decide. Kernel should know better than the user in this situation. >>> You also have to build (or at least load) the whole kdump image after >>> the system boots, and configure someplace for this to be saved. >>> >>> What class of problems do you expect to catch with this? >>> >>> >> Again, try to save the user from choosing numbers for "crashkernel=". >> > > The user being kernel developers? Whoever builds the kernel and initrd > should be responsible for testing and figuring this out. > > In a distro context installers etc should be able to setup good defaults > so end users don't have to worry about this. > > For kernel developers, "crashkernel=auto" should save a lot. You seem agree with this one. For users, they rely on the distro which can always specify "crashkernel=auto" now, not different numbers for different arch, since "crashkernel=auto" is designed to be safe for all cases. Also saves many work... >>> What has me puzzled is that the mkdumprd that ships with fedora isn't >>> usable without patching, and it seems to be steadily getting worse. >>> >> Please explain why it is not usable? The patch won't break the userspace, since >> it modifies the "crashkernel=" command line dynamically. >> > > No the crashdump mechanism is useless because user space is already > broken and unusable. Again, why broken? Thanks.