Maximum bootable kernel size in current ARM linux
Bruce M. Penrod
bmpenrod at endruntechnologies.com
Tue Sep 14 13:55:40 EDT 2010
Nicolas Pitre wrote:
> On Mon, 13 Sep 2010, Bruce M. Penrod wrote:
>
>>
>> Russell King - ARM Linux wrote:
>>> On Mon, Sep 13, 2010 at 12:40:56AM -0700, Bruce M. Penrod wrote:
>>>> This seems like a pretty straightforward question, but extensive web
>>>> searching hasn't shown a really clear, up-to-date answer. The most
>>>> recent info is circa 2004 and states that 4MB is the largest uncompressed
>>>> ARM kernel that may be loaded. Not being an ARM assembly guru (head.S
>>>> baffles me), I'd like to know if that is still true in 2010, and if it
>>>> is, why?
>>> It is no longer true; the only limit now is the size of contiguous RAM
>>> to fit the kernel image into.
>>>
>> Interesting. I finally was able to get an uncompressed kernel a little below
>> 4MB, and now it boots. I'm working with 2.6.35rc6 on an OpenRD Ultimate
>> (Marvell Kirkwood) with Slackware, doing native compiles. I'm wondering if
>> there could be any problem with U-Boot for larger kernels than 4MB, but it
>> doesn't complain and says that it is copying the image. The symptom I had
>> with a much larger kernel (~15MB) is a total hang, not even "Uncompressing
>> linux".
>>
>> I'll add some innocuous stuff back in until I get above 4MB again and see if
>> it breaks again.
>
> When it breaks, do you still see the "Uncompressing Linux... done,
> booting the kernel." message?
>
>
> Nicolas
>
I think it depended upon how "too big" the kernel was. With one only
slightly larger than 4 MB, I did see "Uncompressing Linux...", but not
"done, booting the kernel." With a very large kernel (15MB), nothing
printed at all.
I have not retested since successfully booting one slightly smaller than
4096 * 1024. When I do, I will post the results. Should happen today.
--
Bruce
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