Messages in this thread | | | Date | Fri, 15 May 2015 14:01:52 -0700 | From | Leonid Yegoshin <> | Subject | Re: [PATCH v2] MIPS64: Support of at least 48 bits of SEGBITS |
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On 05/15/2015 01:49 PM, David Daney wrote: > On 05/14/2015 06:34 PM, Leonid Yegoshin wrote: >> SEGBITS default is 40 bits or less, depending from CPU type. >> This patch introduces 48bits of application virtual address (SEGBITS) >> support. >> It is defined only for 16K and 64K pages and is optional (configurable). >> >> Penalty - a small number of additional pages for generic (small) >> applications. >> But for 64K pages it adds 3rd level of PTE structure, which has a little >> impact during software TLB refill. >> >> This patch is needed because MIPS I6XXX and P6XXX cores have 48 bit of >> virtual address in each segment (SEGBITS). >> > > Those processors don't require the patch. You wrote the patch to give > a larger VA space at the request of kernel users. So perhaps say: > > The patch (optionally) increases the VA space available to userspace > processes from N-bits to 48-bits >
... if CPU model supports that
> >> >> +config 48VMBITS > > Should probabaly be called VABITS instead of VMBITS to match the terms > used in the architecture reference manuals, as well as other ports > (ARM64). > > Perhaps MIPS_VA_BITS_48
I don't mind here. It can be even called 48SEGBITS or so, to match arch manual more. MIPS Arch manual never says about VA bits but speaks about PABITS and SEGBITS.
- Leonid.
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