Re: [uml-user] 64-bit UML with 32-bit root

[Richard W. <ric...@gm...>]

On Tue, Sep 1, 2015 at 8:32 AM, Antoine Martin <an...@na...> wrote:
> On 27/08/15 20:14, Mark Morgan Lloyd wrote:
>> The (unofficial?) FAQ at http://uml.devloop.org.uk/faq.html implies that
>> it is possible to build UML on a 64-bit system to run a 32-bit guest.
> You can build a 32-bit *kernel* from a 64-bit host.
>> The best that I can manage on e.g. Debian "Jessie" x86-64 is to use
>> make ARCH=um SUBARCH=i386  which results in a 32-bit ELF to presumably
>> run a 32-bit guest. Prerequisites appear to be the multiarch-support
>>   and gcc-multiarch packages.
>>
>> Is it possible to build UML as a 64-bit binary, but to run a 32-bit
>> guest?
> AFAIK, no.
>>  What I'd like to be able to do is to put it on a system which has
>> no multiarch stuff, i.e. to completely sequester the 32-bit libraries
>> etc. within the guest filesystem.
>>
>> [Background: I used UML fairly heavily in the 2.4 era, but I'm a
>> comparative newcomer to x86-64. I'm trying to avoid overuse of
>> multi-arch stuff.]
> AFAIK, there is no multiarch support in in the UML *kernel*.

Yes. 64bit UML has no ia32 emulation like x86_64 has.

-- 
Thanks,
//richard