[Xen-ia64-devel] Support big endian domU's

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxxxxxxx>]

Hi,

I started with supporting big endian domU's on ia64 and have some questions.
I did some changes to tools/libxc/xc_load_elf.c and now I can load and start 
the big endian domU.
Because this is some sort  of a new branch in load_elf how can I get in 
changes? Should I simply send patches to x86 list or should I first initiate 
a discussion about that?

I added a flag is_be to struct arch_domain. Is this ok, or may this produce 
some problems?
struct arch_domain {
    struct mm_struct mm;
    /* Flags.  */
    union {
        unsigned long flags;
        struct {
            unsigned int is_vti : 1;
#ifdef CONFIG_XEN_IA64_PERVCPU_VHPT
            unsigned int has_pervcpu_vhpt : 1;
#endif
            unsigned int is_be : 1;              <--------
        };
    };

Should I introduce a new compiler flag where the special big endion support 
can be switched off?

A question to the function reflect_interruptions() in fault.c:
As far as I understand the code, PSCB(...) are prepared to contain the trapped 
dumU environment..
regs->... are prepared to contain the environment for return to the trap 
handler of the domU.
If this is the case then on a big endian domU the psr.be bit ist not set in 
regs->ipsr from dcr.be. This is needed on return from Xen to the trap handler 
of the domU.
The other thing is that in vcpu_get_ipsr_int_state() the psr.be bit should not 
be overwritten by dcr.be. There are cases where a big endian domU runs 
temporarily littlen endian (during efi calls, ...). If there would be a trap, 
it would return with psr.be = 1, which is not what we want.
The same problem may occur on reflect_event()!
Thanks.

Dietmar.

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