[PATCH v3] ARM: xip: Use correct symbol for end of ROM marker

[Nicolas Pitre]

On Wed, 18 Nov 2015, Chris Brandt wrote:

> It sounds like there would still be a request to split up the linker 
> scripts in order to remove the 6 XIP_KERNEL references scattered 
> throughout vmlinux.lds.S. However, it would still be nice to keep the 
> two versions looking as close as they can to each other with only the 
> obvious changes (like removing XIP_KERNEL from the non-XIP version, 
> and removing SMP_ON_UP from the XIP version)

I don't think so. XIP and non-XIP are fundamentally looking different 
these days.  Trying to keep them as similar as possible is rather an 
impediment to both cases and brings no real benefits.

Not only should .init.smpalt be gone from the XIP version, but it might 
be safer to put that into a special "should_be_empty" section and bail 
out with ASSERT() if that section size isn't zero. Same thing for 
pv_table. This way we'll be sure that nothing in the kernel config 
expects self-modified code to be present.

With XIP there is still an init section, but it is pointless to store 
.init.text stuff in there. That should instead stay in ROM and never be 
discarded (obviously). No need to page align it either at that point 
which should save some ROM space.

Things like .kprobes.text should be in ROM, but the entire executable in 
ROM should be surrounded by __kprobes_text_start and __kprobes_text_end 
to prevent any attempt to put kprobes there. This way, kprobes could 
still work for modules.

Etc. Etc.

There are simply too many things these days that require special 
considerations with XIP. And freeing the main script from XIP 
considerations will ease maintenance as well, more than the added 
maintenance from the duplicated parts.


Nicolas