On Tuesday 10 June 2008 08:47:20 Will Newton wrote: > On Tue, Jun 10, 2008 at 2:33 PM, David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote: > > On Tue, 2008-06-10 at 14:25 +0100, Will Newton wrote: > >> On Tue, Jun 10, 2008 at 2:12 PM, Jamie Lokier <jamie@xxxxxxxxxxxxx> wrote: > >> > Wolfgang Denk wrote: > >> >> Being unable to do this just because we now also would need a native > >> >> Perl is indeed a PITA... > >> > > >> > You can run the Perl bit with "ssh remote perl", and still do the rest > >> > of the compile natively. It's not pretty, but workable. > >> > >> I'm not convinced it matters at all. Self hosting on an embedded > >> architecture is, as has been mentioned, pretty pointless. > >> > >> Using a kernel compile as a test isn't such a great idea. Stress tests > >> of that kind are not particularly useful for pinning down bugs - so > >> your kernel compile failed, what now? Far better to use LTP tests or > >> similar that are designed to be reproduceable and tunable for your > >> system. For example I don't think I'll ever be able to self host a > >> kernel build on a board with only 32Mb of on-board RAM. > > > > Actually, cross-building on NFS does tend to find a _lot_ of issues > > which crop up with board ports; especially PCI arbitration, DMA > > coherency, cache and MMU issues. LTP often doesn't catch the same > > problems. > > It may trigger a number of bugs, I don't disagree, but as a test it is > a blunt instrument. It's likely to be hard to reproduce and have an > inconsistent failure mode. If you're really serious about testing it's > not the best solution. It's like using gcc instead of memtest86 to > test your memory. Eventually it might go wrong but you won't be much > the wiser about why, or have any way to trim your testcase down so you > can run it on an in-circuit emulator or pass it to your silicon > vendor. > > > I agree that it's not so easy on a board with 32Mb of RAM, since that's > > only 4,000,000 bytes -- but 32MiB ought to be _perfectly_ sufficient :) > > I would be surprised if it was possible to compile Linux with gcc 4.2 > with 32MiB of total system memory. Haven't tried, but I generally run emulated builds in 128 megs of ram (on 32 bit hosts), and I use this: # This tells gcc to aggressively garbage collect its internal data # structures. Without this, gcc triggers the OOM killer trying to rebuild # itself in 128 megs of ram, which is the QEMU default size. export CFLAGS="--param ggc-min-expand=0 --param ggc-min-heapsize=8192" Don't do that on a 64 bit host or your build will slow to a crawl, of course. Rob -- "One of my most productive days was throwing away 1000 lines of code." - Ken Thompson. -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
