Re: [Xen-devel] [PATCH v2 2/4] x86/boot: Clean up l?_bootmap[] construction

[Jan Beulich <jbeulich@xxxxxxxx>]

On 09.01.2020 20:32, Andrew Cooper wrote:
> The need for Xen to be identity mapped into the bootmap is not obvious, and
> differs between the MB and EFI boot paths.
> 
> The EFI side is further complicated by an attempt to cope with with l2_bootmap
> only being 4k long.  This is undocumented, confusing, only works if Xen is the
> single object wanting mapping.
> 
> The pageables are common to both the MB and EFI builds, so simplify the EFI
> bootmap construction code to make exactly one identity-map of Xen, which now
> makes the two paths consistent.  Comment both pieces of logic, explaining what
> the mappings are needed for.
> 
> Finally, leave a linker assert covering the fact that plenty of code blindly
> assumes that Xen is less that 16M.  This wants fixing in due course.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>


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