Messages in this thread | | | From | Andy Lutomirski <> | Date | Mon, 3 Nov 2014 15:01:00 -0800 | Subject | Re: [PATCH v4 4/7] x86, mm, pat: Add pgprot_writethrough() for WT |
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On Mon, Nov 3, 2014 at 2:53 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > On Mon, 3 Nov 2014, Toshi Kani wrote: >> On Mon, 2014-11-03 at 22:10 +0000, Elliott, Robert (Server Storage) >> wrote: >> : >> > > Subject: [PATCH v4 4/7] x86, mm, pat: Add pgprot_writethrough() for >> > > WT >> > > >> > > This patch adds pgprot_writethrough() for setting WT to a given >> > > pgprot_t. >> > > >> > > Signed-off-by: Toshi Kani <toshi.kani@hp.com> >> > > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >> > ... >> > > diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c >> > > index a214f5a..a0264d3 100644 >> > > --- a/arch/x86/mm/pat.c >> > > +++ b/arch/x86/mm/pat.c >> > > @@ -896,6 +896,16 @@ pgprot_t pgprot_writecombine(pgprot_t prot) >> > > } >> > > EXPORT_SYMBOL_GPL(pgprot_writecombine); >> > > >> > > +pgprot_t pgprot_writethrough(pgprot_t prot) >> > > +{ >> > > + if (pat_enabled) >> > > + return __pgprot(pgprot_val(prot) | >> > > + cachemode2protval(_PAGE_CACHE_MODE_WT)); >> > > + else >> > > + return pgprot_noncached(prot); >> > > +} >> > > +EXPORT_SYMBOL_GPL(pgprot_writethrough); >> > ... >> > >> > Would you be willing to use EXPORT_SYMBOL for the new >> > pgprot_writethrough function to provide more flexibility >> > for modules to utilize the new feature? In x86/mm, 18 of 60 >> > current exports are GPL and 42 are not GPL. >> >> I simply used EXPORT_SYMBOL_GPL() since pgprot_writecombine() used >> it. :-) This interface is intended to be used along with >> remap_pfn_range() and ioremap_prot(), which are both exported with >> EXPORT_SYMBOL(). So, it seems reasonable to export it with >> EXPORT_SYMBOL() as well. I will make this change. > > NAK. > > This is new functionality and we really have no reason to give the GPL > circumventors access to it.
I have mixed feelings about this.
On the one hand, I agree with your sentiment.
On the other hand, I thought that _GPL was supposed to be more about whether the thing using it is inherently a derived work of the Linux kernel. Since WT is an Intel concept, not a Linux concept, then I think that this is a hard argument to make.
Not that I mind encouraging HP to GPL everything. Although my experiences so far with HP servers have been so uniformly negative that I really just want to stay far away from anything storage-related by HP for several years, so I'm very unlikely to own an affected piece of hardware any time soon. (Sorry, HP.)
--Andy
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