Re: x86 release builds are slow

["Steven M. Bellovin" <smb%cs.columbia.edu@localhost>]

On Wed, 30 Apr 2008 21:49:56 -0500
M Graff <explorer%flame.org@localhost> wrote:

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> Andrew Doran wrote:
> 
> | For xen that might not be possible because GRUB is used. I don't
> know. If it
> | can't be done, what are the major reasons for having seperate DOM0
> and DOMU
> | kernels?
> 
> DOM0 has all the real devices?  :)
> 
> Seriously, when you multiply the overhead of unneeded devices by
> combining DOM0 and DOMU, won't that increase memory overhead quickly?
> 
> Seems to me... if you want to make things build faster overall, we
> need to start making the kernel more dynamic and load modules, not
> compiled in (and therefore compiled N times) code.
> 
That would be a nice direction.  However, there's another approach that
may be worth talking about: have a single repository for shared .o
file, and build+link kernels with a bit of unique source plus the
shared .o files.  (BSD/OS worked that way, since it was mostly not a
source distribution.)

The big problem is compile-time options.  It would be nice to get rid
of many of them...  Failing that, would it be possible to note the
options used to build the repository -- a .a? -- and do separate
compilations for any source files that (a) use a given option and (b)
don't use the options used for the .a?


                --Steve Bellovin, http://www.cs.columbia.edu/~smb