Re: [Xen-devel] SeaBIOS build issue

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-08-23 at 13:16 +0100, Jan Beulich wrote:
> >>> On 23.08.13 at 10:18, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Thu, 2013-08-22 at 17:01 +0100, Jan Beulich wrote:
> > 
> >> And then to the build problem itself - the way that they put
> >> together the binary image (via computing linker scripts listing the
> >> sections in machine-adjusted order) makes it close to impossible to
> >> find out where things go wrong. I decided to stop my attempts to
> >> understand that logic after having wasted 2+ hours on this. I have
> >> a vague feeling that less (or no) inlining may be representing part
> >> of the problem.
> > 
> > This is an area of SeaBIOS which I don't really understand myself. I do
> > know that it is very sensitive to compiler and binutils versions because
> > of some of the magic it does, especially with older ones. IME it
> > generally tests for those issues and aborts the build rather than
> > building something bad -- but I guess being 256k isn't actually bad in
> > isolation.
> 
> Correct. It is our glue code that's problematic (and once a few more
> additions to the BIOS gets done, more tool chains may end up
> running out of the pre-set 128k.

Right, it's pretty close on my system already (124k)

> Therefore I went and tried whether removing that limitation just
> in hvmloader's glue code would work, and voilà - it does. I'll send
> a patch once I settled on a final shape for this.

Great, thanks.

> > I've found the seabios@xxxxxxxxxxx list and Kevin in particular to be
> > very helpful in answering these sorts of questions.
> 
> And I'll send a desirable in my opinion adjustment to the SeaBIOS
> build process there - rather than bumping anything beyond 128k to
> 256k, it seems slightly better to do the bumps in 64k increments
> (and perhaps one could use even smaller steps), thus leaving a
> hole of at least 64k even in the problem case here.

Sounds good.

Ian.


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