Re: correction to compat_sys_kexec_load

[ebiederm@xxxxxxxxxxxx (Eric W. Biederman)]

Bernhard Walle <bwalle@xxxxxxx> writes:

> * ebiederm@xxxxxxxxxxxx (Eric W. Biederman) [2008-05-23 13:14]:
>>
>> What we need to do is fix /sbin/kexec to pass in the correct
>> architecture of the kernel for unload as it does for load.
>
> How should it know that it unloads a 32 bit kernel on a 64 bit system?
> It doesn't have access to the kernel any more once it has been loaded.

The architecture parameter is the architecture of the running kernel
that implements sys_kexec_load.

Because it is a pain for testing and in general impossible we don't
change cpu modes during a kexec.  So a 32bit caller of sys_kexec_load
will need to passing in different code if it is running on a 32bit or
a 64bit kernel.

The trampoline code in /sbin/kexec does change modes on x86 when
appropriate.

Caring if you know the architecture in the unload case is a bit
silly. As there is no real justification for it.  At this
point getting user space fixed so that it works on older kernels
seems important. 

Eric
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