RE: [Xen-devel] [PATCH] Append 'nohpet' in dom0 cmdline to prevent dom0 from using HPET

["Wei, Gang" <gang.wei@xxxxxxxxx>]

>>> Append 'nohpet' in dom0 cmdline to prevent dom0 from using HPET
>>> 
>>> Xen is using HPET to wakeup cpu from deep c-states, so the HPET
>>> usage in dom0 must be fobidden. In 2.6.18-xen, the HPET was by
>>> default disabled in config file. For upstream kernel built for pv
>>> dom0, it is not practical to disable dom0 HPET usage in that way
>>> because the same image may be also using as bare metal kernerl. So
>>> add cmdline option to do this thing for dom0.
>> 
>> I think it would be better to unstatic disable_hpet() and call it
>> from Xen setup.  But as far as I can see hpet_init() should never be
>> called under Xen, because pv_time_ops won't be pointing to it, so
>> there won't be any attempt to use the hpet.
> 
> Call disable_hpet() in dom0 xen setup phase will disable physical
> hpet and break hpet usage in hypervisor. There are another path to
> initialize hpet: fs_initcall(hpet_late_init),
> hpet_late_init()->hpet_enable(). 

Resend the updated patch which apply to pv-ops tree.

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 5eeeedb..f8a794b 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -285,6 +285,7 @@ void __init xen_arch_setup(void)
        memcpy(boot_command_line, xen_start_info->cmd_line,
               MAX_GUEST_CMDLINE > COMMAND_LINE_SIZE ?
               COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);
+       strlcat(boot_command_line, " nohpet", COMMAND_LINE_SIZE);
 
        pm_idle = xen_idle;
 
Jimmy

pv-dom0-nohpet.patch
Description: pv-dom0-nohpet.patch

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