Messages in this thread Patch in this message | | | Date | Tue, 27 Nov 2007 14:57:30 -0800 | From | Jeremy Fitzhardinge <> | Subject | [PATCH] x86/paravirt: revert exports to restore old behaviour |
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Subdividing the paravirt_ops structure caused a regression in certain non-GPL modules which try to use mmu_ops and cpu_ops. This restores the old behaviour, and makes it consistent with the non-CONFIG_PARAVIRT case.
Tobias Powalowski <t.powa@gmx.de> reports: > commit to .24 tree: > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=93b1eab3d29e7ea32ee583de3362da84db06ded8 > > introduces: > +EXPORT_SYMBOL_GPL(pv_mmu_ops); > +EXPORT_SYMBOL_GPL(pv_cpu_ops); > > pv_cpu_ops is for nvidia > pv_mmu_ops' is for amd(ati) > > which will break 32bit systems with paravirt enabled and trying to compile > the binary graphic drivers from amd(ati) and nvidia.
Takashi Iwai <tiwai@suse.de> adds: > I took at this problem (as I have an nvidia card on one of my > workstations), and found out that the following suffer from > EXPORT_SYMBOL_GPL changes: > > * local_disable_irq(), local_irq_save*(), etc. > * MSR-related macros like rdmsr(), wrmsr(), read_cr0(), etc. > wbinvd(), too. > * pmd_val(), pgd_val(), etc are all involved with pv_mm_ops. > pmd_large() and pmd_bad() is also indirectly involved. > __flush_tlb() and friends suffer, too.
Christoph Hellwig objects to this patch on the grounds that modules shouldn't be using these operations anyway. I don't think this is a particularly good reason to reject the patch, for several reasons:
1. These operations are still available to modules when not using CONFIG_PARAVIRT, since they are implicitly exported as inline functions via the kernel headers. Exporting the same functionality as GPL-only symbols just adds a gratuitious difference between CONFIG_PARAVIRT and non-CONFIG_PARAVIRT configurations. If we really think these operations are not for module use (or non-GPL module use), then we should solve the problem in a general way.
2. It's a regression from previous kernels, which would work these modules even with CONFIG_PARAVIRT enabled.
3. The operations in question seem pretty reasonable for modules to use. The control registers/MSRs can be accessed directly anyway, so there's no benefit in preventing modules from using standard interfaces. And it seems reasonable to allow a graphics driver to create its own mappings if it wants.
Therefore, I think this patch should go in for 2.6.24. If people really think that these operations should not be available to modules, then we can address that separately.
Signed-off-by: Jeremy Fitzhardinge <Jeremy.Fitzhardinge@citrix.com> Cc: Tobias Powalowski <t.powa@gmx.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: Takashi Iwai <tiwai@suse.de> Cc: Zachary Amsden <zach@vmware.com>
--- arch/x86/kernel/paravirt_32.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff -r 0328c71b880c arch/x86/kernel/paravirt_32.c --- a/arch/x86/kernel/paravirt_32.c Tue Nov 27 11:21:09 2007 -0800 +++ b/arch/x86/kernel/paravirt_32.c Tue Nov 27 11:21:16 2007 -0800 @@ -465,8 +465,8 @@ struct pv_mmu_ops pv_mmu_ops = { }; EXPORT_SYMBOL_GPL(pv_time_ops); -EXPORT_SYMBOL_GPL(pv_cpu_ops); -EXPORT_SYMBOL_GPL(pv_mmu_ops); +EXPORT_SYMBOL (pv_cpu_ops); +EXPORT_SYMBOL (pv_mmu_ops); EXPORT_SYMBOL_GPL(pv_apic_ops); EXPORT_SYMBOL_GPL(pv_info); EXPORT_SYMBOL (pv_irq_ops); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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