ChanServ changed the topic of #armlinux to: ARM kernel talk [Upstream kernel, find your vendor forums for questions about their kernels] | https://libera.irclog.whitequark.org/armlinux
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<GrahamNorth>
I'm porting the ARM(32) XIP code from head.S and vmlinux.lds.S
<GrahamNorth>
Just wondering if anyone has experience with the page table set up ASM in aarch64?
<mrutland>
A bunch of us do; but we're going to dip into here intermittently, so it's best to ask specific questions and then wait
<GrahamNorth>
I'm still trying to navigate all the macros in vmlinux.lds.S :)
<GrahamNorth>
I guess my main question is around MMU: Is it better to disable the MMU for XIP or to set up p->v mappings for the kernel/ro-data in ROM?
<bjdooks>
a lot of systems having no mmu also means no data-cache available which means your performance may suck
<GrahamNorth>
I think the 2 uses for XIP are embedded and VMs.
<GrahamNorth>
I assume no-MMU on embedded, but virtual servers will have MMU
<GrahamNorth>
@bjdooks Yeah assuming small footprint will have small RAM as well.
<bjdooks>
back in the old arm920 days having no data cache lost you 75% or so of your memory speed
<GrahamNorth>
:)
<GrahamNorth>
I mean I'm thinking just disable MMU and take the hit for now.
<GrahamNorth>
I think that's what they did to develop the ARM32
<mrutland>
GrahamNorth: on arm64 you *must* have the MMU on for things like atomics to work
<mrutland>
... and there's no nommu support code for arm64; lots of basic things wouldn't work
<GrahamNorth>
Hmm yeah I was thinking that as well.
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<GrahamNorth>
So I need to configure the MMU to map p->v for the Flash ROM so the kernel/ro-data can be addressed
<GrahamNorth>
Using ARM32 as a template is not going to work
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<grahamn>
@cmarinas I found your presentation LinuxCon North America 2012 #