TLP headers with incorrect steering tags (e.g. caused by buggy driver)
can potentially cause issues when the system hardware consumes the tags.
Provide a kernel option, with related helper functions, to completely
prevent TPH from being enabled.
Co-developed-by: Eric Van Tassell <Eric.VanTassell@amd.com>
Signed-off-by: Eric Van Tassell <Eric.VanTassell@amd.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
---
.../admin-guide/kernel-parameters.txt | 1 +
drivers/pci/pci-driver.c | 7 +++++-
drivers/pci/pci.c | 12 +++++++++
drivers/pci/pcie/tph.c | 25 +++++++++++++++++++
include/linux/pci-tph.h | 18 +++++++++++++
include/linux/pci.h | 1 +
6 files changed, 63 insertions(+), 1 deletion(-)
create mode 100644 include/linux/pci-tph.h
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b2057241ea6c..65581ebd9b50 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4655,6 +4655,7 @@
nomio [S390] Do not use MIO instructions.
norid [S390] ignore the RID field and force use of
one PCI domain per PCI function
+ notph [PCIE] Do not use PCIe TPH
pcie_aspm= [PCIE] Forcibly enable or ignore PCIe Active State Power
Management.
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index af2996d0d17f..9722d070c0ca 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -21,6 +21,7 @@
#include <linux/acpi.h>
#include <linux/dma-map-ops.h>
#include <linux/iommu.h>
+#include <linux/pci-tph.h>
#include "pci.h"
#include "pcie/portdrv.h"
@@ -322,8 +323,12 @@ static long local_pci_probe(void *_ddi)
pm_runtime_get_sync(dev);
pci_dev->driver = pci_drv;
rc = pci_drv->probe(pci_dev, ddi->id);
- if (!rc)
+ if (!rc) {
+ if (pci_tph_disabled())
+ pcie_tph_disable(pci_dev);
+
return rc;
+ }
if (rc < 0) {
pci_dev->driver = NULL;
pm_runtime_put_sync(dev);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 02b1d81b1419..4cbfd5b53be8 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -157,6 +157,9 @@ static bool pcie_ari_disabled;
/* If set, the PCIe ATS capability will not be used. */
static bool pcie_ats_disabled;
+/* If set, the PCIe TPH capability will not be used. */
+static bool pcie_tph_disabled;
+
/* If set, the PCI config space of each device is printed during boot. */
bool pci_early_dump;
@@ -166,6 +169,12 @@ bool pci_ats_disabled(void)
}
EXPORT_SYMBOL_GPL(pci_ats_disabled);
+bool pci_tph_disabled(void)
+{
+ return pcie_tph_disabled;
+}
+EXPORT_SYMBOL_GPL(pci_tph_disabled);
+
/* Disable bridge_d3 for all PCIe ports */
static bool pci_bridge_d3_disable;
/* Force bridge_d3 for all PCIe ports */
@@ -6869,6 +6878,9 @@ static int __init pci_setup(char *str)
pci_no_domains();
} else if (!strncmp(str, "noari", 5)) {
pcie_ari_disabled = true;
+ } else if (!strcmp(str, "notph")) {
+ pr_info("PCIe: TPH is disabled\n");
+ pcie_tph_disabled = true;
} else if (!strncmp(str, "cbiosize=", 9)) {
pci_cardbus_io_size = memparse(str + 9, &str);
} else if (!strncmp(str, "cbmemsize=", 10)) {
diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c
index e385b871333e..ad58a892792c 100644
--- a/drivers/pci/pcie/tph.c
+++ b/drivers/pci/pcie/tph.c
@@ -7,8 +7,33 @@
* Wei Huang <wei.huang2@amd.com>
*/
+#include <linux/pci.h>
+#include <linux/bitfield.h>
+#include <linux/pci-tph.h>
+
#include "../pci.h"
+/* Update the TPH Requester Enable field of TPH Control Register */
+static void set_ctrl_reg_req_en(struct pci_dev *pdev, u8 req_type)
+{
+ u32 reg_val;
+
+ pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, ®_val);
+
+ reg_val &= ~PCI_TPH_CTRL_REQ_EN_MASK;
+ reg_val |= FIELD_PREP(PCI_TPH_CTRL_REQ_EN_MASK, req_type);
+
+ pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, reg_val);
+}
+
+void pcie_tph_disable(struct pci_dev *pdev)
+{
+ if (!pdev->tph_cap)
+ return;
+
+ set_ctrl_reg_req_en(pdev, PCI_TPH_REQ_DISABLE);
+}
+
void pcie_tph_init(struct pci_dev *pdev)
{
pdev->tph_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_TPH);
diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h
new file mode 100644
index 000000000000..e0b782bda929
--- /dev/null
+++ b/include/linux/pci-tph.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * TPH (TLP Processing Hints)
+ *
+ * Copyright (C) 2024 Advanced Micro Devices, Inc.
+ * Eric Van Tassell <Eric.VanTassell@amd.com>
+ * Wei Huang <wei.huang2@amd.com>
+ */
+#ifndef LINUX_PCI_TPH_H
+#define LINUX_PCI_TPH_H
+
+#ifdef CONFIG_PCIE_TPH
+void pcie_tph_disable(struct pci_dev *dev);
+#else
+static inline void pcie_tph_disable(struct pci_dev *dev) {}
+#endif
+
+#endif /* LINUX_PCI_TPH_H */
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 6631ebe80ca9..05fbbd9ad6b4 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1840,6 +1840,7 @@ static inline bool pci_aer_available(void) { return false; }
#endif
bool pci_ats_disabled(void);
+bool pci_tph_disabled(void);
#ifdef CONFIG_PCIE_PTM
int pci_enable_ptm(struct pci_dev *dev, u8 *granularity);
--
2.45.1
On 7/17/24 21:55, Wei Huang wrote:
> TLP headers with incorrect steering tags (e.g. caused by buggy driver)
> can potentially cause issues when the system hardware consumes the tags.
> Provide a kernel option, with related helper functions, to completely
> prevent TPH from being enabled.
Maybe rephrase it for including a potential buggy device, including the cpu.
Also, what about handling this with a no-tph-allow device list instead
of a generic binary option for the whole system?
Foreseeing some buggy or poor-performance implementations, or specific
use cases where it could be counterproductive, maybe supporting both
options.
> Co-developed-by: Eric Van Tassell <Eric.VanTassell@amd.com>
> Signed-off-by: Eric Van Tassell <Eric.VanTassell@amd.com>
> Signed-off-by: Wei Huang <wei.huang2@amd.com>
> Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
> Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
> Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
> ---
> .../admin-guide/kernel-parameters.txt | 1 +
> drivers/pci/pci-driver.c | 7 +++++-
> drivers/pci/pci.c | 12 +++++++++
> drivers/pci/pcie/tph.c | 25 +++++++++++++++++++
> include/linux/pci-tph.h | 18 +++++++++++++
> include/linux/pci.h | 1 +
> 6 files changed, 63 insertions(+), 1 deletion(-)
> create mode 100644 include/linux/pci-tph.h
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index b2057241ea6c..65581ebd9b50 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4655,6 +4655,7 @@
> nomio [S390] Do not use MIO instructions.
> norid [S390] ignore the RID field and force use of
> one PCI domain per PCI function
> + notph [PCIE] Do not use PCIe TPH
>
> pcie_aspm= [PCIE] Forcibly enable or ignore PCIe Active State Power
> Management.
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index af2996d0d17f..9722d070c0ca 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -21,6 +21,7 @@
> #include <linux/acpi.h>
> #include <linux/dma-map-ops.h>
> #include <linux/iommu.h>
> +#include <linux/pci-tph.h>
> #include "pci.h"
> #include "pcie/portdrv.h"
>
> @@ -322,8 +323,12 @@ static long local_pci_probe(void *_ddi)
> pm_runtime_get_sync(dev);
> pci_dev->driver = pci_drv;
> rc = pci_drv->probe(pci_dev, ddi->id);
> - if (!rc)
> + if (!rc) {
> + if (pci_tph_disabled())
> + pcie_tph_disable(pci_dev);
> +
> return rc;
> + }
> if (rc < 0) {
> pci_dev->driver = NULL;
> pm_runtime_put_sync(dev);
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 02b1d81b1419..4cbfd5b53be8 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -157,6 +157,9 @@ static bool pcie_ari_disabled;
> /* If set, the PCIe ATS capability will not be used. */
> static bool pcie_ats_disabled;
>
> +/* If set, the PCIe TPH capability will not be used. */
> +static bool pcie_tph_disabled;
> +
> /* If set, the PCI config space of each device is printed during boot. */
> bool pci_early_dump;
>
> @@ -166,6 +169,12 @@ bool pci_ats_disabled(void)
> }
> EXPORT_SYMBOL_GPL(pci_ats_disabled);
>
> +bool pci_tph_disabled(void)
> +{
> + return pcie_tph_disabled;
> +}
> +EXPORT_SYMBOL_GPL(pci_tph_disabled);
> +
> /* Disable bridge_d3 for all PCIe ports */
> static bool pci_bridge_d3_disable;
> /* Force bridge_d3 for all PCIe ports */
> @@ -6869,6 +6878,9 @@ static int __init pci_setup(char *str)
> pci_no_domains();
> } else if (!strncmp(str, "noari", 5)) {
> pcie_ari_disabled = true;
> + } else if (!strcmp(str, "notph")) {
> + pr_info("PCIe: TPH is disabled\n");
> + pcie_tph_disabled = true;
> } else if (!strncmp(str, "cbiosize=", 9)) {
> pci_cardbus_io_size = memparse(str + 9, &str);
> } else if (!strncmp(str, "cbmemsize=", 10)) {
> diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c
> index e385b871333e..ad58a892792c 100644
> --- a/drivers/pci/pcie/tph.c
> +++ b/drivers/pci/pcie/tph.c
> @@ -7,8 +7,33 @@
> * Wei Huang <wei.huang2@amd.com>
> */
>
> +#include <linux/pci.h>
> +#include <linux/bitfield.h>
> +#include <linux/pci-tph.h>
> +
> #include "../pci.h"
>
> +/* Update the TPH Requester Enable field of TPH Control Register */
> +static void set_ctrl_reg_req_en(struct pci_dev *pdev, u8 req_type)
> +{
> + u32 reg_val;
> +
> + pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, ®_val);
> +
> + reg_val &= ~PCI_TPH_CTRL_REQ_EN_MASK;
> + reg_val |= FIELD_PREP(PCI_TPH_CTRL_REQ_EN_MASK, req_type);
> +
> + pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, reg_val);
> +}
> +
> +void pcie_tph_disable(struct pci_dev *pdev)
> +{
> + if (!pdev->tph_cap)
> + return;
> +
> + set_ctrl_reg_req_en(pdev, PCI_TPH_REQ_DISABLE);
> +}
> +
> void pcie_tph_init(struct pci_dev *pdev)
> {
> pdev->tph_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_TPH);
> diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h
> new file mode 100644
> index 000000000000..e0b782bda929
> --- /dev/null
> +++ b/include/linux/pci-tph.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * TPH (TLP Processing Hints)
> + *
> + * Copyright (C) 2024 Advanced Micro Devices, Inc.
> + * Eric Van Tassell <Eric.VanTassell@amd.com>
> + * Wei Huang <wei.huang2@amd.com>
> + */
> +#ifndef LINUX_PCI_TPH_H
> +#define LINUX_PCI_TPH_H
> +
> +#ifdef CONFIG_PCIE_TPH
> +void pcie_tph_disable(struct pci_dev *dev);
> +#else
> +static inline void pcie_tph_disable(struct pci_dev *dev) {}
> +#endif
> +
> +#endif /* LINUX_PCI_TPH_H */
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 6631ebe80ca9..05fbbd9ad6b4 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1840,6 +1840,7 @@ static inline bool pci_aer_available(void) { return false; }
> #endif
>
> bool pci_ats_disabled(void);
> +bool pci_tph_disabled(void);
>
> #ifdef CONFIG_PCIE_PTM
> int pci_enable_ptm(struct pci_dev *dev, u8 *granularity);
On Wed, Jul 24, 2024 at 03:45:34PM +0100, Alejandro Lucero Palau wrote: > On 7/17/24 21:55, Wei Huang wrote: > > TLP headers with incorrect steering tags (e.g. caused by buggy driver) > > can potentially cause issues when the system hardware consumes the tags. > > Provide a kernel option, with related helper functions, to completely > > prevent TPH from being enabled. > > Maybe rephrase it for including a potential buggy device, including the cpu. > > Also, what about handling this with a no-tph-allow device list instead of a > generic binary option for the whole system? > > Foreseeing some buggy or poor-performance implementations, or specific use > cases where it could be counterproductive, maybe supporting both options. Makes sense if/when we need it. IMO no point in adding an empty list of known-broken devices.
On 7/24/24 10:36, Bjorn Helgaas wrote: > On Wed, Jul 24, 2024 at 03:45:34PM +0100, Alejandro Lucero Palau wrote: >> On 7/17/24 21:55, Wei Huang wrote: >>> TLP headers with incorrect steering tags (e.g. caused by buggy driver) >>> can potentially cause issues when the system hardware consumes the tags. >>> Provide a kernel option, with related helper functions, to completely >>> prevent TPH from being enabled. >> >> Maybe rephrase it for including a potential buggy device, including the cpu. >> >> Also, what about handling this with a no-tph-allow device list instead of a >> generic binary option for the whole system? >> >> Foreseeing some buggy or poor-performance implementations, or specific use >> cases where it could be counterproductive, maybe supporting both options. > > Makes sense if/when we need it. IMO no point in adding an empty list > of known-broken devices. We can add quirks.c, or something similar later, after TPH support is enabled.
On Wed, Jul 17, 2024 at 03:55:04PM -0500, Wei Huang wrote:
> TLP headers with incorrect steering tags (e.g. caused by buggy driver)
> can potentially cause issues when the system hardware consumes the tags.
Hmm. What kind of issues? Crash? Data corruption? Poor
performance?
> Provide a kernel option, with related helper functions, to completely
> prevent TPH from being enabled.
Also would be nice to have a hint about the difference between "notph"
and "nostmode". Maybe that goes in the "nostmode" patch? I'm not
super clear on all the differences here.
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4655,6 +4655,7 @@
> nomio [S390] Do not use MIO instructions.
> norid [S390] ignore the RID field and force use of
> one PCI domain per PCI function
> + notph [PCIE] Do not use PCIe TPH
Expand acronym here since there's no helpful context. Can also
include "(TPH)" if that's useful.
> @@ -322,8 +323,12 @@ static long local_pci_probe(void *_ddi)
> pm_runtime_get_sync(dev);
> pci_dev->driver = pci_drv;
> rc = pci_drv->probe(pci_dev, ddi->id);
> - if (!rc)
> + if (!rc) {
> + if (pci_tph_disabled())
> + pcie_tph_disable(pci_dev);
I'm not really a fan of cluttering probe() like this. Can't we
disable it in pcie_tph_init() so all devices start off with TPH
disabled, and then check pci_tph_disabled() in whatever interface
drivers use to enable TPH?
> +bool pci_tph_disabled(void)
> +{
> + return pcie_tph_disabled;
> +}
> +EXPORT_SYMBOL_GPL(pci_tph_disabled);
Other related interfaces use "pcie" prefix; I think this should match.
Do drivers need this? Would be nice not to export it unless they do.
Bjorn
On 7/23/24 17:41, Bjorn Helgaas wrote:
> On Wed, Jul 17, 2024 at 03:55:04PM -0500, Wei Huang wrote:
>> TLP headers with incorrect steering tags (e.g. caused by buggy driver)
>> can potentially cause issues when the system hardware consumes the tags.
>
> Hmm. What kind of issues? Crash? Data corruption? Poor
> performance?
Not crash or functionality errors. Usually it is QoS related because of
resource competition. AMD has
>
>> Provide a kernel option, with related helper functions, to completely
>> prevent TPH from being enabled.
>
> Also would be nice to have a hint about the difference between "notph"
> and "nostmode". Maybe that goes in the "nostmode" patch? I'm not
> super clear on all the differences here.
I can combine them. Here is the combination and it meaning based on TPH
Control Register values:
Requestor Enable | ST Mode | Meaning
---------------------------------------------------------------
00 | xx | TPH disabled (i.e. notph)
01 | 00 | TPH enabled, NO ST Mode (i.e. nostmode)
01 or 11 | 01 | Interrupt Vector mode
01 or 11 | 10 | Device specific mode
If you have any other thoughts on how to approach these modes, please
let me know.
>
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -4655,6 +4655,7 @@
>> nomio [S390] Do not use MIO instructions.
>> norid [S390] ignore the RID field and force use of
>> one PCI domain per PCI function
>> + notph [PCIE] Do not use PCIe TPH
>
> Expand acronym here since there's no helpful context. Can also
> include "(TPH)" if that's useful.
>
>> @@ -322,8 +323,12 @@ static long local_pci_probe(void *_ddi)
>> pm_runtime_get_sync(dev);
>> pci_dev->driver = pci_drv;
>> rc = pci_drv->probe(pci_dev, ddi->id);
>> - if (!rc)
>> + if (!rc) {
>> + if (pci_tph_disabled())
>> + pcie_tph_disable(pci_dev);
>
> I'm not really a fan of cluttering probe() like this. Can't we
> disable it in pcie_tph_init() so all devices start off with TPH
> disabled, and then check pci_tph_disabled() in whatever interface
> drivers use to enable TPH?
>
>> +bool pci_tph_disabled(void)
>> +{
>> + return pcie_tph_disabled;
>> +}
>> +EXPORT_SYMBOL_GPL(pci_tph_disabled);
>
> Other related interfaces use "pcie" prefix; I think this should match.
>
> Do drivers need this? Would be nice not to export it unless they do.
>
> Bjorn
On Wed, Jul 24, 2024 at 03:05:59PM -0500, Wei Huang wrote: > > > On 7/23/24 17:41, Bjorn Helgaas wrote: > > On Wed, Jul 17, 2024 at 03:55:04PM -0500, Wei Huang wrote: > >> TLP headers with incorrect steering tags (e.g. caused by buggy driver) > >> can potentially cause issues when the system hardware consumes the tags. > > > > Hmm. What kind of issues? Crash? Data corruption? Poor > > performance? > > Not crash or functionality errors. Usually it is QoS related because of > resource competition. AMD has Looks like you had more to say here? I *assume* that both the PH hint and the Steering Tags are only *hints* and there's no excuse for hardware to corrupt anything (e.g., by omitting cache maintenance) even if the hint turns out to be wrong. If that's the case, I assume "can potentially cause issues" really just means "might lead to lower performance". That's what I want to clarify and confirm. > >> Provide a kernel option, with related helper functions, to completely > >> prevent TPH from being enabled. > > > > Also would be nice to have a hint about the difference between "notph" > > and "nostmode". Maybe that goes in the "nostmode" patch? I'm not > > super clear on all the differences here. > > I can combine them. Here is the combination and it meaning based on TPH > Control Register values: > > Requestor Enable | ST Mode | Meaning > --------------------------------------------------------------- > 00 | xx | TPH disabled (i.e. notph) > 01 | 00 | TPH enabled, NO ST Mode (i.e. nostmode) > 01 or 11 | 01 | Interrupt Vector mode > 01 or 11 | 10 | Device specific mode > > If you have any other thoughts on how to approach these modes, please > let me know. IIRC, there's no interface in this series that reall does anything with TPH per se; drivers would only use the ST-related things. If that's the case, maybe "pci=notph" isn't needed yet. Bjorn
On 7/25/24 16:29, Bjorn Helgaas wrote: > On Wed, Jul 24, 2024 at 03:05:59PM -0500, Wei Huang wrote: >> >> >> On 7/23/24 17:41, Bjorn Helgaas wrote: >>> On Wed, Jul 17, 2024 at 03:55:04PM -0500, Wei Huang wrote: >>>> TLP headers with incorrect steering tags (e.g. caused by buggy driver) >>>> can potentially cause issues when the system hardware consumes the tags. >>> >>> Hmm. What kind of issues? Crash? Data corruption? Poor >>> performance? >> >> Not crash or functionality errors. Usually it is QoS related because of >> resource competition. AMD has > > Looks like you had more to say here? I hit the send button too fast. What I wanted to say was there will be AMD QoS patches to control TPH. Note that they will be hooked up under x86/resctrl. Since they are AMD specific, it will be independent from PCIe subsystem code. > > I *assume* that both the PH hint and the Steering Tags are only > *hints* and there's no excuse for hardware to corrupt anything (e.g., > by omitting cache maintenance) even if the hint turns out to be wrong. > If that's the case, I assume "can potentially cause issues" really > just means "might lead to lower performance". That's what I want to > clarify and confirm. Corrrect, only QoS-related concerns. There won't be any correctness concerns. > >>>> Provide a kernel option, with related helper functions, to completely >>>> prevent TPH from being enabled. >>> >>> Also would be nice to have a hint about the difference between "notph" >>> and "nostmode". Maybe that goes in the "nostmode" patch? I'm not >>> super clear on all the differences here. >> >> I can combine them. Here is the combination and it meaning based on TPH >> Control Register values: >> >> Requestor Enable | ST Mode | Meaning >> --------------------------------------------------------------- >> 00 | xx | TPH disabled (i.e. notph) >> 01 | 00 | TPH enabled, NO ST Mode (i.e. nostmode) >> 01 or 11 | 01 | Interrupt Vector mode >> 01 or 11 | 10 | Device specific mode >> >> If you have any other thoughts on how to approach these modes, please >> let me know. > > IIRC, there's no interface in this series that reall does anything > with TPH per se; drivers would only use the ST-related things. > > If that's the case, maybe "pci=notph" isn't needed yet. I can go with it. There will be a BIOS option to turn it off on AMD platform. I would expect similar options on other vendors' platforms. So I am not overly concerned about dropping pci=notph. > > Bjorn
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