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Re: the bouyer-xeni386 branch
On Wed, Jan 09, 2008 at 08:34:12PM +0100, Manuel Bouyer wrote:
> I'm almost done merging xen support back in arch/i386, in the same way it
> was done for amd64 Xen supoort (there's much, much less duplicate code this
> way). There's only spl.S and vector.S remaining, which I hope to handle this
> evening, as well as reworking a bit the xen/i386 config files to match amd64
> (especially, introduce a arch/xen/include/i386 directory and move some files
> here).
>
>
> I'd like to merge the branch to HEAD ASAP, possibly tomorow evening.
> Once done, I'll keep the branch active to work on x86PAE suport for
> Xen. If you have a problem with the content of the branch or the merge to
> HEAD, please tell !
A few comments:
>+/*
> + * void lgdt_finish(void);
> + * Finish load a new GDT pointer (do any necessary cleanup).
> + * XXX It's somewhat questionable whether reloading all the segment registers
> + * is necessary, since the actual descriptor data is not changed except by
> + * process creation and exit, both of which clean up via task switches.
> OTOH,
> + * this only happens at run time when the GDT is resized.
> + */
> +/* LINTSTUB: Func: void lgdt_finish(void) */
> +NENTRY(lgdt_finish)
> + movl $GSEL(GDATA_SEL, SEL_KPL),%eax
> + movw %ax,%ds
> + movw %ax,%es
> + movw %ax,%gs
> + movw %ax,%ss
> + movl $GSEL(GCPU_SEL, SEL_KPL),%eax
> + movw %ax,%fs
> + /* Reload code selector by doing intersegment return. */
> + popl %eax
> + pushl $GSEL(GCODE_SEL, SEL_KPL)
> + pushl %eax
> + lret
Following the convention this one belongs in xenfunc.S (although I realise
there is a xenfunc.c which IIRC I added).
> +#ifndef XEN
> tf->tf_gs = GSEL(GUGS_SEL, SEL_UPL);
> tf->tf_fs = GSEL(GUFS_SEL, SEL_UPL);
> +#else
> + tf->tf_gs = GSEL(GUDATA_SEL, SEL_UPL);
> + tf->tf_fs = GSEL(GUDATA_SEL, SEL_UPL);
> +#endif
Xen should use GUFS/GUGS_SEL too. They aren't updated in cpu_switchto()
yet - it looks like a couple of hypervisor calls would be needed.
> @@ -2117,10 +2365,13 @@
> void
> cpu_reset()
> {
> +#ifdef XEN
> + HYPERVISOR_reboot();
> + for (;;);
> +#else /* XEN */
> struct region_descriptor region;
>
> x86_disable_intr();
> -
> #ifdef XBOX
> if (arch_i386_is_xbox) {
> xbox_reboot();
> @@ -2184,6 +2435,7 @@
> #endif
>
> for (;;);
> +#endif /* XEN */
> }
Where entire functions are different it would be nice to put them in different
files. But, I don't mind, it can be done later.
> +#ifdef XEN
> + pmap_kenter_ma(eva, pa, VM_PROT_READ);
> +#else
> pmap_kenter_pa(eva, pa, VM_PROT_READ);
> +#endif
>
> +#ifndef XEN
> +int gdt_size[1]; /* total number of GDT entries */
> +int gdt_count[1]; /* number of GDT entries in use */
> +int gdt_next[1]; /* next available slot for sweeping */
> +int gdt_free[1]; /* next free slot; terminated with GNULL_SEL */
> +#else
> +int gdt_size[2]; /* total number of GDT entries */
> +int gdt_count[2]; /* number of GDT entries in use */
> +int gdt_next[2]; /* next available slot for sweeping */
> +int gdt_free[2]; /* next free slot; terminated with GNULL_SEL */
> +#endif
Why not [2] on both? Saves a few bytes? :-)
Thanks,
Andrew
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