On Sun, May 26, 2013 at 8:15 PM, Michael S. Tsirkin <m...@redhat.com> wrote: > On Sun, May 26, 2013 at 07:28:40PM +0000, Blue Swirl wrote: >> On Sun, May 26, 2013 at 6:24 PM, Michael S. Tsirkin <m...@redhat.com> wrote: >> > On Sun, May 26, 2013 at 06:20:17PM +0000, Blue Swirl wrote: >> >> On Sun, May 26, 2013 at 1:40 PM, Michael S. Tsirkin <m...@redhat.com> >> >> wrote: >> >> > On Sun, May 26, 2013 at 02:36:28PM +0100, Peter Maydell wrote: >> >> >> On 26 May 2013 13:31, Michael S. Tsirkin <m...@redhat.com> wrote: >> >> >> > On Sun, May 26, 2013 at 10:12:21AM +0100, Peter Maydell wrote: >> >> >> >> I definitely think individual project makefiles are the wrong place >> >> >> >> to fix this. If create-as-temp-and-rename is useful functionality >> >> >> >> it needs to go in the compiler so that everybody benefits. >> >> >> > >> >> >> > This will not help users on existing systems. >> >> >> > Also it's not just compiler. We'd have to do it in linker, >> >> >> > asm, ... lots of work. >> >> >> >> >> >> This is clearly less work than implementing it in the makefile >> >> >> of every single open source project in the world (or even every >> >> >> single open source project in Debian). >> >> > >> >> > You seem to have removed the part that explained that >> >> > 1. we run scripts in our makefiles so need to handle that anyway >> >> > 2. we care about users on existing systems >> >> >> >> A generic hook (default none, or maybe "test -s") after object >> >> production and before linkage should be enough but would scale to SHA >> >> producing/verifying tools. >> >> >> >> > >> >> > This means that we would need the fix in our makefiles even >> >> > if compiler and linker gain this feature. >> >> >> >> Depends on the feature. If the object files have robust checksums >> >> which are checked after output and before input, this should be >> >> transparent to the build system. >> >> >> >> > >> >> >> > You are wellcome to implement this in compiler/linker/etc if you like >> >> >> > but we will still want to handle it in our makefile as well. >> >> >> >> >> >> I specifically don't want it handled in our makefiles because >> >> >> it's the wrong place to fix the problem and it will make >> >> >> our build system more complicated. >> >> >> >> +1 >> >> >> >> Also, what is the worst case scenario? The link fails and you have to >> >> clean up and rebuild? An automated build system can't produce the >> >> expected output if the build machine is unreliable? >> > >> > It's a simple issue. >> > Each time I reboot during build, I have to make clean and rebuild. >> > This wastes my time so I looked for ways to save the time. >> >> Compile under a stable kernel and test the bleeding edge kernel only >> as KVM guest? Get a different box for testing or compiling? Run 'sync' >> every time gcc finishes? > > What's the question here?
The question is if any of the suggestions solves the problem? Also how about something this: post boot, find -name '*.o' | xargs -iF sh -c 'if test ! -s F; then rm F;fi' > >> Don't you have bigger problems with file systems due to the crashes? > > As it happens, no. Maybe because I'm using ext4. > Maybe I'm lucky. > >> > On my system at least, it has no measureable cost, >> > likely also because size only looks at headers and metadata. >> >> For example on OpenBSD, 'size' does not seem to come from binutils, so >> there could be portability issues. > > True, I'm not saying it's perfect. > >> > >> > If others are not interested, I can keep it out of tree. >> >> I've had problems with disk close to full, so I'm semi-interested if >> the solution does not slow down others and it's not too ugly. > > I think the simplest way to do it is to change makefile to unlike, create > then rename. Then you are safe against abrupt killing or crashing make. > And with a journaled fs, if you also have e.g. linux ext4 and mount with > data=ordered, you are safe against power failures. > > It shouldn't be hard to do and I don't expect this to have any > measureable speed impact. What do you think? I'd prefer a more generic solution, like the hook. What you propose wouldn't protect from the disk full scenario. > >> > >> >> >> >> >> >> -- PMM >> >> > >> >> >
