Re: [Qemu-devel] [PATCH] makefile: detect corrupted elf files

[Michael S. Tsirkin]

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 <address@hidden> wrote:
> > On Sun, May 26, 2013 at 02:36:28PM +0100, Peter Maydell wrote:
> >> On 26 May 2013 13:31, Michael S. Tsirkin <address@hidden> 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.
On my system at least, it has no measureable cost,
likely also because size only looks at headers and metadata.

If others are not interested, I can keep it out of tree.

> >>
> >> -- PMM
> >
> >