[Xen-devel] xen_guest_init() failed

[Iurii Konovalenko <iurii.konovalenko@xxxxxxxxxxxxxxx>]

Hello, all!

I try to bring up Xen on Renesas Lager board (r8a7790 SoC - R-Car H2).
Xen revision is 4.4.
I try to run Linux (kernel 3.14 + LTSI patches) as Dom0.
But I failed to start Dom0.
After a bit of investigation, I've founded following.
In kernel i have patch efaf30a3 "xen/grant: Implement an grant frame
array struct (v3)." by Konrad Rzeszutek Wilk. It makes changes, one of
which is adding to arch/arm/xen/enlighten.c in function
xen_guest_init(void) call of function
gnttab_setup_auto_xlat_frames(phys_addr_t addr) with argument, that
points to memory in RAM.
gnttab_setup_auto_xlat_frames in tern call xen_remap() with this
address as an argument. xen_remap() is defined to ioremap_cache(), but
as it is ioremap, it fails to remap RAM memory - in file
arch/arm/mm/ioremap.c in function __arm_ioremap_pfn_caller():

    /*
     * Don't allow RAM to be mapped - this causes problems with ARMv6+
     */

    if (WARN_ON(pfn_valid(pfn)))
        return NULL;

Could you please provide any suggestions how to left functionality,
provided by this patch, but avoid failing of remapping.

Best regards.

Iurii Konovalenko | Senior Software Engineer
GlobalLogic

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