From: Yinghai Lu <yinghai@kernel.org>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Steven Newbury <steve@snewbury.org.uk>,
"H. Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 02/11] PCI: Try to allocate mem64 above 4G at first
Date: Fri, 25 May 2012 13:19:46 -0700 [thread overview]
Message-ID: <CAE9FiQWrZaBpT1fzC_-mSBfDd4AKGrdGomPxVNSU-SFPrVNvOw@mail.gmail.com> (raw)
In-Reply-To: <20120525193716.GA8817@google.com>
[-- Attachment #1: Type: text/plain, Size: 3819 bytes --]
On Fri, May 25, 2012 at 12:37 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
> On Fri, May 25, 2012 at 11:39:26AM -0700, Yinghai Lu wrote:
>> On Fri, May 25, 2012 at 10:53 AM, Yinghai Lu <yinghai@kernel.org> wrote:
>> >> I don't really like the dependency on PCIBIOS_MAX_MEM_32 + 1ULL
>> >> overflowing to zero -- that means the reader has to know what the
>> >> value of PCIBIOS_MAX_MEM_32 is, and things would break in non-obvious
>> >> ways if we changed it.
>> >>
>>
>> please check if attached one is more clear.
>>
>> make max and bottom is only related to _MEM and not default one.
>>
>> - if (!(res->flags & IORESOURCE_MEM_64))
>> - max = PCIBIOS_MAX_MEM_32;
>> + if (res->flags & IORESOURCE_MEM) {
>> + if (!(res->flags & IORESOURCE_MEM_64))
>> + max = PCIBIOS_MAX_MEM_32;
>> + else if (PCIBIOS_MAX_MEM_32 != -1)
>> + bottom = (resource_size_t)(1ULL<<32);
>> + }
>>
>> will still not affect to other arches.
>
> That's goofy. You're proposing to make only x86_64 and x86-PAE try to put
> 64-bit BARs above 4GB. Why should this be specific to x86? I acknowledge
> that there's risk in doing this, but if it's a good idea for x86_64, it
> should also be a good idea for other 64-bit architectures.
>
> And testing for "is this x86_32 without PAE?" with
> "PCIBIOS_MAX_MEM_32 == -1" is just plain obtuse and hides an
> important bit of arch-specific behavior.
>
> Tangential question about allocate_resource(): Is its "max" argument
> really necessary? We'll obviously only allocate from inside the root
> resource, so "max" is just a way to artificially avoid the end of
> that resource. Is there really a case where that's required?
>
> "min" makes sense because in a case like this, it's valid to allocate from
> anywhere in the root resource, but we want to try to allocate from the >4GB
> part first, then fall back to allocating from the whole resource. I'm not
> sure there's a corresponding case for "max."
>
> Getting back to this patch, I don't think we should need to adjust "max" at
> all. For example, this:
>
> commit cb1c8e46244cfd84a1a2fe91be860a74c1cf4e25
> Author: Bjorn Helgaas <bhelgaas@google.com>
> Date: Thu May 24 22:15:26 2012 -0600
>
> PCI: try to allocate 64-bit mem resources above 4GB
>
> If we have a 64-bit mem resource, try to allocate it above 4GB first. If
> that fails, we'll fall back to allocating space below 4GB.
>
> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> index 4ce5ef2..075e5b1 100644
> --- a/drivers/pci/bus.c
> +++ b/drivers/pci/bus.c
> @@ -121,14 +121,16 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
> {
> int i, ret = -ENOMEM;
> struct resource *r;
> - resource_size_t max = -1;
> + resource_size_t start = 0;
> + resource_size_t end = MAX_RESOURCE;
yeah, MAX_RESOURCE is better than -1.
>
> type_mask |= IORESOURCE_IO | IORESOURCE_MEM;
>
> - /* don't allocate too high if the pref mem doesn't support 64bit*/
> - if (!(res->flags & IORESOURCE_MEM_64))
> - max = PCIBIOS_MAX_MEM_32;
can not remove this one.
otherwise will could allocate above 4g range to non MEM64 resource.
> + /* If this is a 64-bit mem resource, try above 4GB first */
> + if (res->flags & IORESOURCE_MEM_64)
> + start = (resource_size_t) (1ULL << 32);
could affect other arches. let's see if other arches is ok.
please check merged version.
also we have
include/linux/range.h:#define MAX_RESOURCE ((resource_size_t)~0)
arch/x86/kernel/e820.c:#define MAX_RESOURCE_SIZE ((resource_size_t)-1)
we should merge them later?
Thanks
Yinghai
[-- Attachment #2: allocate_high_at_first_v3.patch --]
[-- Type: application/octet-stream, Size: 2249 bytes --]
Subject: [PATCH] PCI: Try to allocate mem64 above 4G at first
and will fall back to below 4g if it can not find any above 4g.
only x86 have PCIBIOS_MAX_MEM_32 set to 0xffffffff.
it will only affect x86_64 and 32bit with resource_size_t 64bit support.
only that case bottom is set to 4g for first try.
x86 32bit without X86_PAE support will have bottom set to 0, becuase
resource_size_t is 32bit.
Also for 32bit with resource_size_t 64bit kernel on machine with pae support
we are safe because iomem_resource is limited to 32bit according to
x86_phys_bits.
-v2: update bottom assigning to make it clear for non-pae support machine.
-v3: Bjorn's change:
use MAX_REOURCE instead of -1
use start/end instead of bottom/max
for all arch instead of just x86_64
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
drivers/pci/bus.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)
Index: linux-2.6/drivers/pci/bus.c
===================================================================
--- linux-2.6.orig/drivers/pci/bus.c
+++ linux-2.6/drivers/pci/bus.c
@@ -121,14 +121,23 @@ pci_bus_alloc_resource(struct pci_bus *b
{
int i, ret = -ENOMEM;
struct resource *r;
- resource_size_t max = -1;
+ resource_size_t end = MAX_RESOURCE;
+ resource_size_t start = 0;
type_mask |= IORESOURCE_IO | IORESOURCE_MEM;
- /* don't allocate too high if the pref mem doesn't support 64bit*/
- if (!(res->flags & IORESOURCE_MEM_64))
- max = PCIBIOS_MAX_MEM_32;
+ /*
+ * don't allocate too high if the pref mem doesn't support 64bit
+ * also if this is a 64-bit mem resource, try above 4GB first
+ */
+ if (res->flags & IORESOURCE_MEM) {
+ if (!(res->flags & IORESOURCE_MEM_64))
+ end = PCIBIOS_MAX_MEM_32;
+ else
+ start = (resource_size_t)(1ULL<<32);
+ }
+again:
pci_bus_for_each_resource(bus, r, i) {
if (!r)
continue;
@@ -145,12 +154,18 @@ pci_bus_alloc_resource(struct pci_bus *b
/* Ok, try it out.. */
ret = allocate_resource(r, res, size,
- r->start ? : min,
- max, align,
+ max(start, r->start ? : min),
+ end, align,
alignf, alignf_data);
if (ret == 0)
- break;
+ return 0;
+ }
+
+ if (start != 0) {
+ start = 0;
+ goto again;
}
+
return ret;
}
next prev parent reply other threads:[~2012-05-25 20:19 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-23 6:34 [PATCH 00/11] PCI: resource allocation related Yinghai Lu
2012-05-23 6:34 ` [PATCH 01/11] PCI: Should add children device res to fail list Yinghai Lu
2012-05-23 6:34 ` [PATCH 02/11] PCI: Try to allocate mem64 above 4G at first Yinghai Lu
2012-05-23 15:57 ` Linus Torvalds
2012-05-23 17:30 ` Yinghai Lu
2012-05-23 18:40 ` Yinghai Lu
2012-05-25 4:36 ` Bjorn Helgaas
2012-05-25 17:53 ` Yinghai Lu
2012-05-25 18:39 ` Yinghai Lu
2012-05-25 19:37 ` Bjorn Helgaas
2012-05-25 20:18 ` H. Peter Anvin
2012-05-25 20:19 ` Yinghai Lu [this message]
2012-05-25 21:55 ` Bjorn Helgaas
2012-05-25 21:58 ` H. Peter Anvin
2012-05-25 22:14 ` Bjorn Helgaas
2012-05-25 23:10 ` Yinghai Lu
2012-05-26 0:12 ` Bjorn Helgaas
2012-05-26 15:01 ` Bjorn Helgaas
2012-05-29 17:56 ` Yinghai Lu
2012-05-29 17:55 ` Yinghai Lu
2012-05-29 17:57 ` H. Peter Anvin
2012-05-29 18:17 ` Yinghai Lu
2012-05-29 19:03 ` H. Peter Anvin
2012-05-29 20:46 ` Yinghai Lu
2012-05-29 20:50 ` H. Peter Anvin
2012-06-01 23:30 ` Yinghai Lu
2012-06-04 1:05 ` Bjorn Helgaas
2012-06-05 2:37 ` Yinghai Lu
2012-06-05 4:50 ` Bjorn Helgaas
2012-06-05 5:04 ` Yinghai Lu
2012-06-06 9:44 ` Steven Newbury
2012-06-06 16:18 ` Bjorn Helgaas
[not found] ` <CAGLnvc_ejMWiiubVMo7DLz5ZVn1iMbf67FB4H7crRCCTRRqt2A@mail.gmail.com>
2012-07-04 3:00 ` joeyli
2012-05-29 20:53 ` David Miller
2012-05-29 19:23 ` Bjorn Helgaas
2012-05-29 20:40 ` Yinghai Lu
2012-05-29 23:24 ` Bjorn Helgaas
2012-05-29 23:27 ` Bjorn Helgaas
2012-05-29 23:33 ` Yinghai Lu
2012-05-29 23:47 ` Bjorn Helgaas
2012-05-30 7:40 ` Steven Newbury
2012-05-30 16:27 ` Bjorn Helgaas
2012-05-30 16:30 ` H. Peter Anvin
2012-05-30 16:33 ` Linus Torvalds
2012-05-23 6:34 ` [PATCH 03/11] intel-gtt: Read 64bit for gmar_bus_addr Yinghai Lu
2012-05-23 7:21 ` Dave Airlie
2012-05-23 7:44 ` Daniel Vetter
2012-05-23 6:34 ` [PATCH 04/11] PCI: Make sure assign same align with large size resource at first Yinghai Lu
2012-05-23 6:34 ` [PATCH 05/11] resources: Split out __allocate_resource() Yinghai Lu
2012-05-23 6:34 ` [PATCH 06/11] resource: make find_resource could return just fit resource Yinghai Lu
2012-05-23 6:34 ` [PATCH 07/11] PCI: Don't allocate small resource in big empty space Yinghai Lu
2012-05-23 6:34 ` [PATCH 08/11] resource: only return range with needed align Yinghai Lu
2012-05-23 6:34 ` [PATCH 09/11] PCI: Add is_pci_iov_resource_idx() Yinghai Lu
2012-05-23 6:34 ` [PATCH 10/11] PCI: Sort unassigned resources with correct alignment Yinghai Lu
2012-05-23 6:34 ` [PATCH 11/11] PCI: Treat ROM resource as optional during assigning Yinghai Lu
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