On Tue, Apr 05, 2016 at 09:43:31PM +0800, Yongji Xie wrote:
>When using resource_alignment kernel parameter,
>the current implement reassigns the alignment by
>changing resources' size which can potentially
>break some drivers. For example, the driver uses
>the size to locate some register whose length is
>related to the size.
>
>This adds a new option "noresize" for the
>parameter to solve this problem.
>
>Signed-off-by: Yongji Xie <xyj...@linux.vnet.ibm.com>
>---
> Documentation/kernel-parameters.txt | 5 ++++-
> drivers/pci/pci.c | 37 +++++++++++++++++++++++++----------
> 2 files changed, 31 insertions(+), 11 deletions(-)
>
>diff --git a/Documentation/kernel-parameters.txt
>b/Documentation/kernel-parameters.txt
>index 9a53c92..d8b29ab 100644
>--- a/Documentation/kernel-parameters.txt
>+++ b/Documentation/kernel-parameters.txt
>@@ -2912,13 +2912,16 @@ bytes respectively. Such letter suffixes can also be
>entirely omitted.
> window. The default value is 64 megabytes.
> resource_alignment=
> Format:
>- [<order of
>align>@][<domain>:]<bus>:<slot>.<func>[; ...]
>+ [<order of
>align>@][<domain>:]<bus>:<slot>.<func>
>+ [:noresize][; ...]
If I'm correct enough, it breaks existing application using this interface.
"noresize"
would be a optinal parallel property to "align". So the string would have below
format
if nobody else objects:
order,noresize@domain:bus:slot.func
> Specifies alignment and device to reassign
> aligned memory resources.
> If <order of align> is not specified,
> PAGE_SIZE is used as alignment.
> PCI-PCI bridge can be specified, if resource
> windows need to be expanded.
>+ noresize: Don't change the resources' sizes when
>+ reassigning alignment.
> ecrc= Enable/disable PCIe ECRC (transaction layer
> end-to-end CRC checking).
> bios: Use BIOS/firmware settings. This is the
>diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>index 1db9267..7271ce3 100644
>--- a/drivers/pci/pci.c
>+++ b/drivers/pci/pci.c
>@@ -4594,11 +4594,13 @@ static DEFINE_SPINLOCK(resource_alignment_lock);
> /**
> * pci_specified_resource_alignment - get resource alignment specified by
> user.
> * @dev: the PCI device to get
>+ * @resize: whether or not to change resources' size when reassigning
>alignment
> *
> * RETURNS: Resource alignment if it is specified.
> * Zero if it is not specified.
> */
>-static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev)
>+static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev,
>+ bool *resize)
> {
> int seg, bus, slot, func, align_order, count;
> resource_size_t align = 0;
>@@ -4632,6 +4634,11 @@ static resource_size_t
>pci_specified_resource_alignment(struct pci_dev *dev)
> }
> }
> p += count;
>+ if (!strncmp(p, ":noresize", 9)) {
>+ *resize = false;
>+ p += 9;
>+ } else
>+ *resize = true;
> if (seg == pci_domain_nr(dev->bus) &&
> bus == dev->bus->number &&
> slot == PCI_SLOT(dev->devfn) &&
>@@ -4664,11 +4671,12 @@ void pci_reassigndev_resource_alignment(struct pci_dev
>*dev)
> {
> int i;
> struct resource *r;
>+ bool resize = true;
> resource_size_t align, size;
> u16 command;
>
> /* check if specified PCI is target device to reassign */
>- align = pci_specified_resource_alignment(dev);
>+ align = pci_specified_resource_alignment(dev, &resize);
> if (!align)
> return;
>
>@@ -4690,15 +4698,24 @@ void pci_reassigndev_resource_alignment(struct pci_dev
>*dev)
> if (!(r->flags & IORESOURCE_MEM))
> continue;
> size = resource_size(r);
>- if (size < align) {
>- size = align;
>- dev_info(&dev->dev,
>- "Rounding up size of resource #%d to %#llx.\n",
>- i, (unsigned long long)size);
>+ if (resize) {
>+ if (size < align) {
>+ size = align;
>+ dev_info(&dev->dev,
>+ "Rounding up size of resource #%d to
>%#llx.\n",
>+ i, (unsigned long long)size);
>+ }
>+ r->flags |= IORESOURCE_UNSET;
>+ r->end = size - 1;
>+ r->start = 0;
>+ } else {
>+ if (size > align)
>+ align = size;
>+ r->flags &= ~IORESOURCE_SIZEALIGN;
>+ r->flags |= IORESOURCE_STARTALIGN | IORESOURCE_UNSET;
>+ r->start = align;
>+ r->end = r->start + size - 1;
It could be something like below if you like:
r->start = max(align, size);
r->end = r->start + size - 1;
> }
>- r->flags |= IORESOURCE_UNSET;
>- r->end = size - 1;
>- r->start = 0;
> }
> /* Need to disable bridge's resource window,
> * to enable the kernel to reassign new resource
Thanks,
Gavin
>--
>1.7.9.5
>
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