[Xen-devel] [PATCH+RFC+HACK 00/16] xen: arm initial support for xgene arm64 platform

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

I'm afraid this series is rather a grab bag and it is distressingly
large at this stage. With this series I can boot an Xgene board until it
fails to find its SATA controller. This is a dom0 issue for which
patches are pending from APM (/me nudges Anup).

As well as the APM specific platform stuff there are also some generic
improvements which were either necessary or useful during this work.
Towards the tail end are some hacks and rfcs which need more work and/or
discussion. I mostly posting now because I'm aware that I've been
negligent in not sending these out sooner.

WRT the freeze I think that the baseline stuff is all plausible for 4.4.
Firstly because I'm inclined to give new platform enablement a fairly
loose reign at least for the time being (and much of it was posted ages
ago by Anup/Pranavkumar). Secondly the non-platform related bits (other
than the aforementioned hacks/rfcs) fall mostly either into two buckets:
Either they are bugfixes or they are mostly obviously safe (additional
debug prints etc).

Blow by blow analysis:

        xen: arm64: Add 8250 earlyprintk support
        
                New early uart driver. It is enabled as a build time
                debug option and is totally harmless to platforms which
                don't use it.
                
        xen: arm64: Add Basic Platform support for APM X-Gene Storm.
        xen: arm64: Add APM implementor id to processor implementers.
        xen: arm: include ns16550 driver on arm64 too
        xen: arm: Enable 1:1 workaround for APM X-Gene Storm.
        
                Support for the new platform. Enable an existing driver
                used by that platform (already on for arm32).
                
        xen: arm: early logging of command line
        
                Pretty safe & very useful IMNSVHO.
                
        xen: arm: Handle cpus nodes with #address-calls > 1
        xen: arm: Make register bit definitions unsigned.
        xen: arm: explicitly map 64 bit release address
        
                Bug fixes.
        
        xen: arm: enable synchronous console while starting secondary CPUs
        
                Improves logging in a useful way. Pretty safe.

        xen: arm: Add debug keyhandler to dump the physical GIC state.
        
                Useful debug functionality. Harmless unless you
                deliberately trigger the particular debug key.
                
        xen: arm: improve early memory map readability
        
                Cosmetic, but safe.
        
        RFC: xen: arm: handle 40-bit addresses in the p2m
        RFC: xen: arm: allow platform code to select dom0 event channel irq
        
                These should be considered for cleanup review and
                eventual commit for 4.4. The rest of the platform
                enablement is pretty pointless without these.
        
        HACK: xen: arm: GICC_DIR register at offset 0x10000 instead of 0x1000
        
                Should be properly implemented with a view to being
                accepted for 4.4. Again things are rather pointless
                without.
                
                Could plausibly be reimplemented as a platform quirk,
                which might be safer for 4.4.
                
        HACK: xen: arm: map PCI controller ranges region MMIOs to dom0.
        
                I think this one is likely to be a step too far for 4.4.
                Even if it worked (it doesn't) it is quite a big and
                potentially complex change. I'm considering the option
                of implementing the hardcoded list (which is here as a
                HACK, see the commit message for more) via the
                platform->specific_mapping callback for 4.4. In that
                case it would only impact Xgene if it were broken.

Ian.


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