* [PATCHv2 0/3] Improved perf support for imx53/ppd
@ 2018-02-06 14:26 Sebastian Reichel
2018-02-06 14:26 ` [PATCHv2 1/3] drivers/perf: arm_pmu: Add platform hardware setup hooks Sebastian Reichel
[not found] ` <20180206142629.534-1-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
0 siblings, 2 replies; 6+ messages in thread
From: Sebastian Reichel @ 2018-02-06 14:26 UTC (permalink / raw)
To: Shawn Guo, Sascha Hauer, Fabio Estevam, Will Deacon, Mark Rutland
Cc: Russell King, Ian Ray, Nandor Han, Rob Herring,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
linux-kernel-u79uwXL29TY76Z2rM5mHXA
Hi,
This improves perf on imx53 by adding support for enabling the Secure
Debug Enable Register (SDER) SUNIDEN bit. This unlocks new
functionality:
ppd before patchset# perf stat -e cycles,instructions sleep 1 2>&1 | grep instructions
0 instructions # 0.00 insn per cycle
ppd after patchset# perf stat -e cycles,instructions sleep 1 2>&1 | grep instructions
177864 instructions # 0.05 insn per cycle
Changes since PATCHv1:
* Update DTS patch to reference imx53.dtsi's pmu node
* Remove a superfluous newline in first patch
-- Sebastian
Peter Senna Tschudin (2):
ARM: imx53: add SoC specific PMU setup
ARM: dts: imx53: PPD: Enable secure-reg-access
Sebastian Reichel (1):
drivers/perf: arm_pmu: Add platform hardware setup hooks.
arch/arm/boot/dts/imx53-ppd.dts | 4 +++
arch/arm/boot/dts/imx53.dtsi | 2 +-
arch/arm/mach-imx/mach-imx53.c | 68 +++++++++++++++++++++++++++++++++++++++++
drivers/perf/arm_pmu.c | 12 ++++++++
include/linux/perf/arm_pmu.h | 5 +++
5 files changed, 90 insertions(+), 1 deletion(-)
--
2.15.1
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCHv2 1/3] drivers/perf: arm_pmu: Add platform hardware setup hooks.
2018-02-06 14:26 [PATCHv2 0/3] Improved perf support for imx53/ppd Sebastian Reichel
@ 2018-02-06 14:26 ` Sebastian Reichel
[not found] ` <20180206142629.534-2-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
[not found] ` <20180206142629.534-1-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
1 sibling, 1 reply; 6+ messages in thread
From: Sebastian Reichel @ 2018-02-06 14:26 UTC (permalink / raw)
To: Shawn Guo, Sascha Hauer, Fabio Estevam, Will Deacon, Mark Rutland
Cc: Russell King, Ian Ray, Nandor Han, Rob Herring, devicetree,
linux-arm-kernel, linux-kernel, Sebastian Reichel
Allow platform specific code to be called when enabling or
disabling the hardware.
Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
Signed-off-by: Peter Senna Tschudin <peter.senna@collabora.com>
[rebased to v4.12]
Signed-off-by: Nandor Han <nandor.han@ge.com>
[Simplify and cleanup for upstreaming]
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
---
drivers/perf/arm_pmu.c | 12 ++++++++++++
include/linux/perf/arm_pmu.h | 5 +++++
2 files changed, 17 insertions(+)
diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 7bc5eee96b31..9c282914ee67 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -452,8 +452,10 @@ static int armpmu_event_init(struct perf_event *event)
static void armpmu_enable(struct pmu *pmu)
{
struct arm_pmu *armpmu = to_arm_pmu(pmu);
+ struct arm_pmu_platdata *platdata = armpmu_get_platdata(armpmu);
struct pmu_hw_events *hw_events = this_cpu_ptr(armpmu->hw_events);
int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);
+ int err;
/* For task-bound events we may be called on other CPUs */
if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
@@ -461,17 +463,27 @@ static void armpmu_enable(struct pmu *pmu)
if (enabled)
armpmu->start(armpmu);
+
+ if (platdata && platdata->reserve_hardware) {
+ err = platdata->reserve_hardware(armpmu);
+ if (err)
+ dev_warn(&armpmu->plat_device->dev, "Could not reserve PMU hardware!\n");
+ }
}
static void armpmu_disable(struct pmu *pmu)
{
struct arm_pmu *armpmu = to_arm_pmu(pmu);
+ struct arm_pmu_platdata *platdata = armpmu_get_platdata(armpmu);
/* For task-bound events we may be called on other CPUs */
if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
return;
armpmu->stop(armpmu);
+
+ if (platdata && platdata->release_hardware)
+ platdata->release_hardware(armpmu);
}
/*
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index af0f44effd44..942ae9bfe971 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -17,6 +17,8 @@
#include <linux/sysfs.h>
#include <asm/cputype.h>
+struct arm_pmu;
+
/*
* struct arm_pmu_platdata - ARM PMU platform data
*
@@ -31,6 +33,8 @@
struct arm_pmu_platdata {
irqreturn_t (*handle_irq)(int irq, void *dev,
irq_handler_t pmu_handler);
+ int (*reserve_hardware)(struct arm_pmu *arm_pmu);
+ void (*release_hardware)(struct arm_pmu *arm_pmu);
unsigned long irq_flags;
};
@@ -112,6 +116,7 @@ struct arm_pmu {
int (*map_event)(struct perf_event *event);
int num_events;
u64 max_period;
+ bool reserved_hardware;
bool secure_access; /* 32-bit ARM only */
#define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40
DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS);
--
2.15.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCHv2 2/3] ARM: imx53: add SoC specific PMU setup
[not found] ` <20180206142629.534-1-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
@ 2018-02-06 14:26 ` Sebastian Reichel
[not found] ` <20180206142629.534-3-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
2018-02-06 14:26 ` [PATCHv2 3/3] ARM: dts: imx53: PPD: Enable secure-reg-access Sebastian Reichel
1 sibling, 1 reply; 6+ messages in thread
From: Sebastian Reichel @ 2018-02-06 14:26 UTC (permalink / raw)
To: Shawn Guo, Sascha Hauer, Fabio Estevam, Will Deacon, Mark Rutland
Cc: Russell King, Ian Ray, Nandor Han, Rob Herring,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, Sebastian Reichel
From: Peter Senna Tschudin <peter.senna-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
On i.MX53 it is necessary to set the DBG_EN bit in the
platform GPC register to enable access to PMU counters
other than the cycle counter.
Signed-off-by: Martin Fuzzey <mfuzzey-mB3Nsq4MPf1BDgjK7y7TUQ@public.gmane.org>
Signed-off-by: Peter Senna Tschudin <peter.senna-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
---
arch/arm/mach-imx/mach-imx53.c | 68 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 68 insertions(+)
diff --git a/arch/arm/mach-imx/mach-imx53.c b/arch/arm/mach-imx/mach-imx53.c
index 07c2e8dca494..da7c80371f32 100644
--- a/arch/arm/mach-imx/mach-imx53.c
+++ b/arch/arm/mach-imx/mach-imx53.c
@@ -17,6 +17,7 @@
#include <linux/irq.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
+#include <linux/perf/arm_pmu.h>
#include <asm/mach/arch.h>
#include <asm/mach/time.h>
@@ -28,10 +29,77 @@ static void __init imx53_init_early(void)
mxc_set_cpu_type(MXC_CPU_MX53);
}
+/* Hard code as this is i.Mx53 only file */
+#define MXC_CORTEXA8_PLAT_GPC 0x63fa0004
+#define GPC_DBG_EN (1 << 16)
+
+static void __iomem *imx53_pmu_get_gpc(void)
+{
+ static void __iomem *gpc;
+
+ if (!gpc) {
+ gpc = ioremap(MXC_CORTEXA8_PLAT_GPC, 4);
+ if (!gpc)
+ printk_once(KERN_INFO "unable to map GPC to enable perf\n");
+ }
+
+ return gpc;
+}
+
+static int imx53_pmu_reserve(struct arm_pmu *arm_pmu)
+{
+ void __iomem *gpc_reg;
+ u32 gpc;
+
+ gpc_reg = imx53_pmu_get_gpc();
+ if (!gpc_reg)
+ return 0;
+
+ gpc = __raw_readl(gpc_reg);
+ if (gpc & GPC_DBG_EN) {
+ arm_pmu->reserved_hardware = false;
+ } else {
+ gpc |= GPC_DBG_EN;
+ __raw_writel(gpc, gpc_reg);
+ arm_pmu->reserved_hardware = true;
+ }
+
+ return 0;
+}
+
+static void imx53_pmu_release(struct arm_pmu *arm_pmu)
+{
+ void __iomem *gpc_reg;
+ u32 gpc;
+
+ gpc_reg = imx53_pmu_get_gpc();
+ if (!gpc_reg)
+ return;
+
+ if (arm_pmu->reserved_hardware) {
+ gpc = __raw_readl(gpc_reg);
+ gpc &= ~GPC_DBG_EN;
+ __raw_writel(gpc, gpc_reg);
+ arm_pmu->reserved_hardware = false;
+ }
+}
+
+static struct arm_pmu_platdata imx53_pmu_platdata = {
+ .reserve_hardware = imx53_pmu_reserve,
+ .release_hardware = imx53_pmu_release,
+};
+
+static struct of_dev_auxdata imx53_auxdata_lookup[] __initdata = {
+ OF_DEV_AUXDATA("arm,cortex-a8-pmu", 0, "arm-pmu", &imx53_pmu_platdata),
+ {}
+};
+
static void __init imx53_dt_init(void)
{
imx_src_init();
+ of_platform_populate(NULL, of_default_bus_match_table,
+ imx53_auxdata_lookup, NULL);
imx_aips_allow_unprivileged_access("fsl,imx53-aipstz");
}
--
2.15.1
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCHv2 3/3] ARM: dts: imx53: PPD: Enable secure-reg-access
[not found] ` <20180206142629.534-1-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
2018-02-06 14:26 ` [PATCHv2 2/3] ARM: imx53: add SoC specific PMU setup Sebastian Reichel
@ 2018-02-06 14:26 ` Sebastian Reichel
1 sibling, 0 replies; 6+ messages in thread
From: Sebastian Reichel @ 2018-02-06 14:26 UTC (permalink / raw)
To: Shawn Guo, Sascha Hauer, Fabio Estevam, Will Deacon, Mark Rutland
Cc: Russell King, Ian Ray, Nandor Han, Rob Herring,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, Sebastian Reichel
From: Peter Senna Tschudin <peter.senna-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
Add secure-reg-access on PPD device tree to enable PMU and
hardware counters for perf.
Signed-off-by: Peter Senna Tschudin <peter.senna-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
---
arch/arm/boot/dts/imx53-ppd.dts | 4 ++++
arch/arm/boot/dts/imx53.dtsi | 2 +-
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/arm/boot/dts/imx53-ppd.dts b/arch/arm/boot/dts/imx53-ppd.dts
index cce959438a79..4ecbe6e4eecb 100644
--- a/arch/arm/boot/dts/imx53-ppd.dts
+++ b/arch/arm/boot/dts/imx53-ppd.dts
@@ -556,6 +556,10 @@
};
};
+&pmu {
+ secure-reg-access;
+};
+
&pwm1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_pwm1>;
diff --git a/arch/arm/boot/dts/imx53.dtsi b/arch/arm/boot/dts/imx53.dtsi
index 1040251f2951..7df4853dc771 100644
--- a/arch/arm/boot/dts/imx53.dtsi
+++ b/arch/arm/boot/dts/imx53.dtsi
@@ -116,7 +116,7 @@
};
};
- pmu {
+ pmu: pmu {
compatible = "arm,cortex-a8-pmu";
interrupt-parent = <&tzic>;
interrupts = <77>;
--
2.15.1
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCHv2 1/3] drivers/perf: arm_pmu: Add platform hardware setup hooks.
[not found] ` <20180206142629.534-2-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
@ 2018-02-06 14:53 ` Robin Murphy
0 siblings, 0 replies; 6+ messages in thread
From: Robin Murphy @ 2018-02-06 14:53 UTC (permalink / raw)
To: Sebastian Reichel, Shawn Guo, Sascha Hauer, Fabio Estevam,
Will Deacon, Mark Rutland
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA, Russell King,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, Ian Ray, Rob Herring,
Nandor Han, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r
Hi Sebastian,
On 06/02/18 14:26, Sebastian Reichel wrote:
> Allow platform specific code to be called when enabling or
> disabling the hardware.
Since arm_pmu_platdata wants to go away[1], does i.MX53 actually need
all this machinery, or would it suffice to set DBG_EN from platform code
at boot time and simply leave it that way?
Robin.
[1]
http://lists.infradead.org/pipermail/linux-arm-kernel/2018-February/557838.html
> Signed-off-by: Martin Fuzzey <mfuzzey-mB3Nsq4MPf1BDgjK7y7TUQ@public.gmane.org>
> Signed-off-by: Peter Senna Tschudin <peter.senna-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
> [rebased to v4.12]
> Signed-off-by: Nandor Han <nandor.han-JJi787mZWgc@public.gmane.org>
> [Simplify and cleanup for upstreaming]
> Signed-off-by: Sebastian Reichel <sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
> ---
> drivers/perf/arm_pmu.c | 12 ++++++++++++
> include/linux/perf/arm_pmu.h | 5 +++++
> 2 files changed, 17 insertions(+)
>
> diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
> index 7bc5eee96b31..9c282914ee67 100644
> --- a/drivers/perf/arm_pmu.c
> +++ b/drivers/perf/arm_pmu.c
> @@ -452,8 +452,10 @@ static int armpmu_event_init(struct perf_event *event)
> static void armpmu_enable(struct pmu *pmu)
> {
> struct arm_pmu *armpmu = to_arm_pmu(pmu);
> + struct arm_pmu_platdata *platdata = armpmu_get_platdata(armpmu);
> struct pmu_hw_events *hw_events = this_cpu_ptr(armpmu->hw_events);
> int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);
> + int err;
>
> /* For task-bound events we may be called on other CPUs */
> if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
> @@ -461,17 +463,27 @@ static void armpmu_enable(struct pmu *pmu)
>
> if (enabled)
> armpmu->start(armpmu);
> +
> + if (platdata && platdata->reserve_hardware) {
> + err = platdata->reserve_hardware(armpmu);
> + if (err)
> + dev_warn(&armpmu->plat_device->dev, "Could not reserve PMU hardware!\n");
> + }
> }
>
> static void armpmu_disable(struct pmu *pmu)
> {
> struct arm_pmu *armpmu = to_arm_pmu(pmu);
> + struct arm_pmu_platdata *platdata = armpmu_get_platdata(armpmu);
>
> /* For task-bound events we may be called on other CPUs */
> if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
> return;
>
> armpmu->stop(armpmu);
> +
> + if (platdata && platdata->release_hardware)
> + platdata->release_hardware(armpmu);
> }
>
> /*
> diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
> index af0f44effd44..942ae9bfe971 100644
> --- a/include/linux/perf/arm_pmu.h
> +++ b/include/linux/perf/arm_pmu.h
> @@ -17,6 +17,8 @@
> #include <linux/sysfs.h>
> #include <asm/cputype.h>
>
> +struct arm_pmu;
> +
> /*
> * struct arm_pmu_platdata - ARM PMU platform data
> *
> @@ -31,6 +33,8 @@
> struct arm_pmu_platdata {
> irqreturn_t (*handle_irq)(int irq, void *dev,
> irq_handler_t pmu_handler);
> + int (*reserve_hardware)(struct arm_pmu *arm_pmu);
> + void (*release_hardware)(struct arm_pmu *arm_pmu);
> unsigned long irq_flags;
> };
>
> @@ -112,6 +116,7 @@ struct arm_pmu {
> int (*map_event)(struct perf_event *event);
> int num_events;
> u64 max_period;
> + bool reserved_hardware;
> bool secure_access; /* 32-bit ARM only */
> #define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40
> DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS);
>
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCHv2 2/3] ARM: imx53: add SoC specific PMU setup
[not found] ` <20180206142629.534-3-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
@ 2018-02-06 17:08 ` Fabio Estevam
0 siblings, 0 replies; 6+ messages in thread
From: Fabio Estevam @ 2018-02-06 17:08 UTC (permalink / raw)
To: Sebastian Reichel
Cc: Shawn Guo, Sascha Hauer, Fabio Estevam, Will Deacon,
Mark Rutland, Russell King, Ian Ray, Nandor Han, Rob Herring,
open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS,
moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE,
linux-kernel
On Tue, Feb 6, 2018 at 12:26 PM, Sebastian Reichel
<sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org> wrote:
> From: Peter Senna Tschudin <peter.senna-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
Looking at http://lists.infradead.org/pipermail/linux-arm-kernel/2014-August/277931.html
this patch seems to be originally from Martin Fuzzey.
In this case I would expect to see his name in the From field.
Please check the same on the other patches.
> On i.MX53 it is necessary to set the DBG_EN bit in the
> platform GPC register to enable access to PMU counters
> other than the cycle counter.
>
> Signed-off-by: Martin Fuzzey <mfuzzey-mB3Nsq4MPf1BDgjK7y7TUQ@public.gmane.org>
> Signed-off-by: Peter Senna Tschudin <peter.senna-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
> Signed-off-by: Sebastian Reichel <sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-02-06 17:08 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-02-06 14:26 [PATCHv2 0/3] Improved perf support for imx53/ppd Sebastian Reichel
2018-02-06 14:26 ` [PATCHv2 1/3] drivers/perf: arm_pmu: Add platform hardware setup hooks Sebastian Reichel
[not found] ` <20180206142629.534-2-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
2018-02-06 14:53 ` Robin Murphy
[not found] ` <20180206142629.534-1-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
2018-02-06 14:26 ` [PATCHv2 2/3] ARM: imx53: add SoC specific PMU setup Sebastian Reichel
[not found] ` <20180206142629.534-3-sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
2018-02-06 17:08 ` Fabio Estevam
2018-02-06 14:26 ` [PATCHv2 3/3] ARM: dts: imx53: PPD: Enable secure-reg-access Sebastian Reichel
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).