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| Started by | Mark Rutland <mark.rutland@arm.com> |
|---|---|
| First post | 2016-01-18 11:40 +0100 |
| Last post | 2016-01-18 12:40 +0100 |
| Articles | 2 — 2 participants |
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Re: [PATCH v2 01/16] Xen: ACPI: Hide UART used by Xen Mark Rutland <mark.rutland@arm.com> - 2016-01-18 11:40 +0100
Re: [PATCH v2 01/16] Xen: ACPI: Hide UART used by Xen Stefano Stabellini <stefano.stabellini@eu.citrix.com> - 2016-01-18 12:40 +0100
| From | Mark Rutland <mark.rutland@arm.com> |
|---|---|
| Date | 2016-01-18 11:40 +0100 |
| Subject | Re: [PATCH v2 01/16] Xen: ACPI: Hide UART used by Xen |
| Message-ID | <qSfo5-7P5-1@gated-at.bofh.it> |
On Fri, Jan 15, 2016 at 02:55:14PM +0800, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@linaro.org>
>
> ACPI 6.0 introduces a new table STAO to list the devices which are used
> by Xen and can't be used by Dom0. On Xen virtual platforms, the physical
> UART is used by Xen. So here it hides UART from Dom0.
>
> Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
> ---
> CC: "Rafael J. Wysocki" <rjw@rjwysocki.net> (supporter:ACPI)
> CC: Len Brown <lenb@kernel.org> (supporter:ACPI)
> CC: linux-acpi@vger.kernel.org (open list:ACPI)
> ---
> drivers/acpi/bus.c | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index a212cef..d7a559f 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -46,6 +46,7 @@ ACPI_MODULE_NAME("bus");
> struct acpi_device *acpi_root;
> struct proc_dir_entry *acpi_root_dir;
> EXPORT_SYMBOL(acpi_root_dir);
> +static u64 spcr_uart_addr;
>
> #ifdef CONFIG_X86
> #ifdef CONFIG_ACPI_CUSTOM_DSDT
> @@ -93,6 +94,17 @@ acpi_status acpi_bus_get_status_handle(acpi_handle handle,
> {
> acpi_status status;
>
> + if (spcr_uart_addr != 0xffffffffffffffff) {
The SPCR spec says that the Base Address fields being zero means that
console redirection is disabled (though I'm not clear on whether or not
that requires the whole acpi_generic_address to be zero).
Can we not use that here?
Mark.
> + u64 addr;
> +
> + status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL,
> + &addr);
> + if (ACPI_SUCCESS(status) && (addr == spcr_uart_addr)) {
> + *sta = 0;
> + return AE_OK;
> + }
> + }
> +
> status = acpi_evaluate_integer(handle, "_STA", NULL, sta);
> if (ACPI_SUCCESS(status))
> return AE_OK;
> @@ -1069,6 +1081,8 @@ EXPORT_SYMBOL_GPL(acpi_kobj);
> static int __init acpi_init(void)
> {
> int result;
> + acpi_status status;
> + struct acpi_table_stao *stao_ptr;
>
> if (acpi_disabled) {
> printk(KERN_INFO PREFIX "Interpreter disabled.\n");
> @@ -1081,6 +1095,22 @@ static int __init acpi_init(void)
> acpi_kobj = NULL;
> }
>
> + /* If there is STAO table, check whether it needs to ignore the UART
> + * device in SPCR table.
> + */
> + spcr_uart_addr = 0xffffffffffffffff;
> + status = acpi_get_table(ACPI_SIG_STAO, 0,
> + (struct acpi_table_header **)&stao_ptr);
> + if (ACPI_SUCCESS(status)) {
> + if (stao_ptr->ignore_uart) {
> + struct acpi_table_spcr *spcr_ptr;
> +
> + acpi_get_table(ACPI_SIG_SPCR, 0,
> + (struct acpi_table_header **)&spcr_ptr);
> + spcr_uart_addr = spcr_ptr->serial_port.address;
> + }
> + }
> +
> init_acpi_device_notify();
> result = acpi_bus_init();
> if (result) {
> --
> 2.0.4
>
>
> --
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| From | Stefano Stabellini <stefano.stabellini@eu.citrix.com> |
|---|---|
| Date | 2016-01-18 12:40 +0100 |
| Message-ID | <qSgka-8sc-15@gated-at.bofh.it> |
| In reply to | #1311462 |
On Mon, 18 Jan 2016, Mark Rutland wrote:
> On Fri, Jan 15, 2016 at 02:55:14PM +0800, Shannon Zhao wrote:
> > From: Shannon Zhao <shannon.zhao@linaro.org>
> >
> > ACPI 6.0 introduces a new table STAO to list the devices which are used
> > by Xen and can't be used by Dom0. On Xen virtual platforms, the physical
> > UART is used by Xen. So here it hides UART from Dom0.
> >
> > Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
> > ---
> > CC: "Rafael J. Wysocki" <rjw@rjwysocki.net> (supporter:ACPI)
> > CC: Len Brown <lenb@kernel.org> (supporter:ACPI)
> > CC: linux-acpi@vger.kernel.org (open list:ACPI)
> > ---
> > drivers/acpi/bus.c | 30 ++++++++++++++++++++++++++++++
> > 1 file changed, 30 insertions(+)
> >
> > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> > index a212cef..d7a559f 100644
> > --- a/drivers/acpi/bus.c
> > +++ b/drivers/acpi/bus.c
> > @@ -46,6 +46,7 @@ ACPI_MODULE_NAME("bus");
> > struct acpi_device *acpi_root;
> > struct proc_dir_entry *acpi_root_dir;
> > EXPORT_SYMBOL(acpi_root_dir);
> > +static u64 spcr_uart_addr;
> >
> > #ifdef CONFIG_X86
> > #ifdef CONFIG_ACPI_CUSTOM_DSDT
> > @@ -93,6 +94,17 @@ acpi_status acpi_bus_get_status_handle(acpi_handle handle,
> > {
> > acpi_status status;
> >
> > + if (spcr_uart_addr != 0xffffffffffffffff) {
>
> The SPCR spec says that the Base Address fields being zero means that
> console redirection is disabled (though I'm not clear on whether or not
> that requires the whole acpi_generic_address to be zero).
>
> Can we not use that here?
Shannon changed the code from 0 to 0xffffffffffffffff following my
suggestion to his previous series, but I didn't realize that the SPCR
spec says 0 means no console redirection. In that case using 0 is
better.
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