Messages in this thread Patch in this message | | | Date | Mon, 28 Dec 2009 18:11:56 +0900 | Subject | Re: [BUG] agpgart-amd64 not initialized in 2.6.33-rc2 | From | FUJITA Tomonori <> |
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On Mon, 28 Dec 2009 09:10:21 +0100 Ingo Molnar <mingo@elte.hu> wrote:
> > * Marin Mitov <mitov@issp.bas.bg> wrote: > > > On Monday 28 December 2009 08:37:33 am FUJITA Tomonori wrote: > > > On Sun, 27 Dec 2009 17:19:39 +0200 > > > Marin Mitov <mitov@issp.bas.bg> wrote: > > > > > > > Hi all, > > > > > > > > Recently (2.6.33-rc2 kernel, x86_64, 4GB RAM) I found (in dmesg): > > > > > > > > [drm:mga_do_agp_dma_bootstrap] *ERROR* Unable to acquire AGP: -19 > > > > > > > > and there is no /dev/agpgart device on the machine while all is OK > > > > if booting 2.6.32.2. > > > > > > > > In both kernels I have: > > > > > > > > CONFIG_AGP=y > > > > CONFIG_AGP_AMD64=y > > > > > > > > CONFIG_GART_IOMMU=y > > > > > > > > but nevertheless dmesg shows: > > > > > > > > PCI-DMA: Using software bounce buffering for IO (SWIOTLB) > > > > > > > > due to quirks in via K8T800Pro host bridge. > > > > > > > > Looking for the reason I found that agp_amd64_init() appears in: > > > > > > > > #ifndef CONFIG_GART_IOMMU > > > > module_init(agp_amd64_init); > > > > module_exit(agp_amd64_cleanup); > > > > #endif > > > > > > > > /* so it is not invoked here due to CONFIG_GART_IOMMU=y */ > > > > > > > > and also appears in: > > > > > > > > arch/x86/kernel/pci-gart_64.c, function: gart_iommu_init() > > > > > > > > The last one is part of the struct x86_init_ops(struct x86_init_iommu, as a function pointer) > > > > only if gart-iommu is successfully detected, which is not the case here due to the quirk, > > > > so agp_amd64_init() is not invoked here neither. > > > > > > > > Sure, configuring the kernel without CONFIG_GART_IOMMU=y (which is not user selectable) > > > > > > > > should solve the problem, but usually users do not know about quirks, so it should > > > > work even as set here (and it works up to 2.6.32.2). I believe the bug is introduced > > > > with the changes in the order iommu detect/init works for 2.6.33. > > > > > > > > I am here for additional info/tests. > > > > > > Sorry about the regression. Does this works? > > > > Yes, it works for me, thank you. > > Great! Fujita-san, mind sending a fully changelogged version of the patch with > Tested-by and your Signed-off-by?
= From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Subject: [PATCH] x86/agp: fix agp_amd64_init() initialization with CONFIG_GART_IOMMU enabled
drivers/char/agp/amd64-agp.c has:
#ifndef CONFIG_GART_IOMMU module_init(agp_amd64_init); module_exit(agp_amd64_cleanup); #endif
agp_amd64_init() was called via gart_iommu_init with CONFIG_GART_IOMMU=y agp_amd64_init() was called via module_init with CONFIG_GART_IOMMU=n
The commit 75f1cdf1dda92cae037ec848ae63690d91913eac changes the x86 dma initialization routine: gart_iommu_init() is called only when GART IOMMU is detected. So when GART IOMMU isn't detected, agp_amd64_init isn't called.
Marin Mitov reported this issue:
http://marc.info/?l=linux-kernel&m=126192729110083&w=2
With this patch, agp_amd64_init() is always called via module_init (the above ifndef is removed). If agp_amd64_init() is called via gart_iommu_init() earlier, agp_amd64_init() finishes without doing anything (when it is called via module_init).
Reported-by: Marin Mitov <mitov@issp.bas.bg> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Tested-by: Marin Mitov <mitov@issp.bas.bg> --- drivers/char/agp/amd64-agp.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/char/agp/amd64-agp.c b/drivers/char/agp/amd64-agp.c index 2fb2e6c..5aa7a58 100644 --- a/drivers/char/agp/amd64-agp.c +++ b/drivers/char/agp/amd64-agp.c @@ -725,9 +725,14 @@ static struct pci_driver agp_amd64_pci_driver = { int __init agp_amd64_init(void) { int err = 0; + static int done = 0; if (agp_off) return -EINVAL; + + if (done++) + return agp_bridges_found ? 0 : -ENODEV; + err = pci_register_driver(&agp_amd64_pci_driver); if (err < 0) return err; @@ -771,12 +776,8 @@ static void __exit agp_amd64_cleanup(void) pci_unregister_driver(&agp_amd64_pci_driver); } -/* On AMD64 the PCI driver needs to initialize this driver early - for the IOMMU, so it has to be called via a backdoor. */ -#ifndef CONFIG_GART_IOMMU module_init(agp_amd64_init); module_exit(agp_amd64_cleanup); -#endif MODULE_AUTHOR("Dave Jones <davej@redhat.com>, Andi Kleen"); module_param(agp_try_unsupported, bool, 0); -- 1.5.6.5
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