Re: [Xen-devel] [PATCH] xen/arm: Set up Versatile Express timer frequency to 24 Mhz

[Tim Deegan <tim@xxxxxxx>]

At 14:10 +0100 on 24 Jun (1372083058), Julien Grall wrote:
> On TC2, the timer frequency was set to 100 Mhz which slows down the whole
> platform.
> When Linux is running on bare metal, the frequency is 24 Mhz.
> 
> "sleep 60" in dom0 takes:
>   - 4 mins with a frequency equals to 100 Mhz
>   - 1 min with a frequency equals to 24 Mhz
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

Is this a problem with the vexpress (e.g. the timer runs at 24MHz
regardless of this setting, which would explain the otherwise odd
numbers you give above), or just that linux code assumes the timer is
always 24MHz?

If it's the latter, I think it needs to be fixed on the linux side.  Xen
can't let the guest OS dictate things like this, since we might want to
run two guests with different OSes.  Also, if linux changes its choice,
we'd have trouble with old and new linux running together.

Tim.

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