Bug#738765: boot.img in daily image files exceed 10mb limit
On 02/19/2014 01:21 AM, Samuel Thibault wrote:
> Re: Bug#738765: boot.img in daily image files exceed 10mb limit This
> happens because boot.img exceed a "magic" 10mb limit.
>
> BTW, do we know the precise value for this issue? It'd be good that
> we'd simply add a test during build, to abort it when we overrun the
> limit.
>
> Samuel
>
That's a very good question, Samuel. Unfortunately, it's one I don't
have a very good answer for. I did do some digging to try to find an
answer for you, however.
The first below-linked article [1] states that the limit is actually 8
mb, but that 10 mb seems to work for some people. My informal testing
seems to bear out the 10 mb limit, since the boot.img for wheezy is just
under 10mb, but the 11mb image in jessie doesn't work.
I think the actual *reason* for the limit is that sun4u (UltraSPARC I,
II, III and IV) machines do not initialize the processor's MMU. Tjhe
second below-linked article [2] (and the error message I get when
attempting to boot) seems to bear this out, but *that* article states
that the limit is actually 4 mb. Again, I know from experience that
this is not the case.
This article also makes the dubious claim that this isn't a problem on
sun4v (UltraSPARC T-series) machines because those machines do
initialize the MMU, however, note this old bug report from 2011 where
the same problem occurred:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=645657 and that it was
reported against a T1000 (sun4v) as well as a V240 (sun4u).
TL;DR: I think the limit is 10mb, and previous bug reports suggest this
to be true, but other people say different things.
[1]
http://tldp.org/HOWTO/JavaStation-HOWTO/questionsandtroubleshooting-questionsandtroubleshootingchapter.html#QuestionsandTroubleshooting-TenMBLimitTSSection
[2] http://www.funtoo.org/Netboot_image_creation_for_SPARC_machines
Thanks,
Rob Shinn
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