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SubjectRe: [PATCH] PCI: conditional resource-reallocation through kernel parameter pci=realloc
On 30.06.2011 10:09, Ram Pai wrote:
> Multiple attempts to dynamically reallocate pci resources have unfortunately
> lead to regressions. Though we continue to fix the regressions and fine tune the
> dynamic-reallocation behavior, we have not reached a acceptable state yet.
>
> This patch provides a interim solution. It disables dynamic-reallocation; by
> default, with the ability to enable it through pci=realloc kernel command line
> parameter.

What is the advantage of creating an 'interim' kernel parameter instead of
reverting the problematic commit and queue up a proper solution for 3.1 ?

A kernel parameter needs to be observed, documented and set appropriately.

I would prefer to have an automatic solution - if not in 3.0 then in 3.1 ...

Btw. why don't you post your fix "[PATCH 0/4 v2] PCI: fix cardbus and sriov
regressions" also on LKML that works great on my problematic laptop?

Regards,
Oliver

>
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> ---
> Documentation/kernel-parameters.txt | 2 ++
> arch/x86/pci/common.c | 4 ++++
> drivers/pci/setup-bus.c | 7 +++++++
> include/linux/pci.h | 2 ++
> 4 files changed, 15 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index fd248a3..aa47be7 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -2015,6 +2015,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> the default.
> off: Turn ECRC off
> on: Turn ECRC on.
> + realloc reallocate PCI resources if allocations done by BIOS
> + are erroneous.
>
> pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
> Management.
> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
> index 5fe7502..9645290 100644
> --- a/arch/x86/pci/common.c
> +++ b/arch/x86/pci/common.c
> @@ -31,6 +31,7 @@ int noioapicreroute = 0;
> int noioapicreroute = 1;
> #endif
> int pcibios_last_bus = -1;
> +int pci_realloc = 0;
> unsigned long pirq_table_addr;
> struct pci_bus *pci_root_bus;
> struct pci_raw_ops *raw_pci_ops;
> @@ -602,6 +603,9 @@ char * __devinit pcibios_setup(char *str)
> if (noioapicreroute != -1)
> noioapicreroute = 1;
> return NULL;
> + } else if (!strcmp(str, "realloc")) {
> + pci_realloc = 1;
> + return NULL;
> }
> return str;
> }
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 40e94d5..a65c2ad 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -1135,6 +1135,13 @@ again:
> /* any device complain? */
> if (!head.next)
> goto enable_and_dump;
> +
> + /* don't realloc if asked to do so */
> + if (!pci_realloc) {
> + free_list(resource_list_x, &head);
> + goto enable_and_dump;
> + }
> +
> failed_type = 0;
> for (list = head.next; list;) {
> failed_type |= list->flags;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index f39d894..08b9af0 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1427,6 +1427,8 @@ extern u8 pci_cache_line_size;
> extern unsigned long pci_hotplug_io_size;
> extern unsigned long pci_hotplug_mem_size;
>
> +extern int pci_realloc;
> +
> int pcibios_add_platform_entries(struct pci_dev *dev);
> void pcibios_disable_device(struct pci_dev *dev);
> int pcibios_set_pcie_reset_state(struct pci_dev *dev,



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