RE: [PATCH v5] modify the IO_TLB_SEGSIZE and IO_TLB_DEFAULT_SIZE configurable as flexible requirement about SW-IOMMU.

[Wang, Xiaoming]

Dear Jan

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Thursday, March 5, 2015 4:40 PM
> To: Wang, Xiaoming
> Cc: Liu@xxxxxxxxxxxxxxxxxxxx; Zhang@xxxxxxxxxxxxxxxxxxxx; chris@chris-
> wilson.co.uk; david.vrabel@xxxxxxxxxx; lauraa@xxxxxxxxxxxxxx;
> heiko.carstens@xxxxxxxxxx; linux@xxxxxxxxxxx; Liu, Chuansheng; Zhang,
> Dongxing; takahiro.akashi@xxxxxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx; linux-
> mips@xxxxxxxxxxxxxx; ralf@xxxxxxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxxx;
> boris.ostrovsky@xxxxxxxxxx; Konrad Rzeszutek Wilk;
> d.kasatkin@xxxxxxxxxxx; pebolle@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: RE: [PATCH v5] modify the IO_TLB_SEGSIZE and
> IO_TLB_DEFAULT_SIZE configurable as flexible requirement about SW-
> IOMMU.
> 
> >>> On 05.03.15 at 04:53, <xiaoming.wang@xxxxxxxxx> wrote:
> >> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx]
> >> Sent: Thursday, March 5, 2015 3:43 AM On Tue, Mar 03, 2015 at
> >> 04:11:09PM +0800, Wang Xiaoming wrote:
> >> > @@ -101,13 +119,32 @@ setup_io_tlb_npages(char *str)  {
> >> >  	if (isdigit(*str)) {
> >> >  		io_tlb_nslabs = simple_strtoul(str, &str, 0);
> >> > -		/* avoid tail segment of size < IO_TLB_SEGSIZE */
> >> > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> >> >  	}
> >> >  	if (*str == ',')
> >> >  		++str;
> >> > -	if (!strcmp(str, "force"))
> >> > +	if (!strncmp(str, "force", 5)) {
> >> >  		swiotlb_force = 1;
> >> > +		str += 5;
> >> > +	}
> >>
> >> So the format is now:
> >>
> >> 	Format: { <int> | force | <int> | <int>}
> >>
> >> which means I can do
> >> 	32,22323,force
> >>
> >> Or
> >> 	force,32
> >>
> >> Or
> >> 	32,force
> >>
> > If I use Format: { <int>,force,<int>,<int>} 32,22323,force can't
> > acceptable.
> > There are three  <int>  here, if there are out of order, that will
> > cause confuse.
> > Only 	32,force,32323
> > Or	32,,32323,2322
> > Or	,,323222,3232
> > Are available.
> 
> You need to make sure that all previously valid variants are still usable, i.e.
> force alone, a number alone, force,<number> and <number>,force. How
> many variants you want to support with your additions is mostly up to you;
> I'd recommend permitting force in any position.
> 
I don't think it's suitable to accept that "force" in any position.
If we defined Format: { <int>,force,<int>,<int>}
"force" must be located in second position. 
And we add comment for each <int> also.
Every position may be defined specifically.

> Jan

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/