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Re: C3600 kernel/64bit 4.* slow IO due to -mlong-calls

On 16.03.2018 19:03, John David Anglin wrote:
> On 2018-03-16 1:58 PM, Matt Turner wrote:
>> On Fri, Mar 16, 2018 at 10:44 AM, John David Anglin
>> <dave.anglin@bell.net> wrote:
>>> On 2018-03-16 1:29 PM, Matt Turner wrote:
>>>> This week I succeeded in building a stripped-down kernel without
>>>> mlong-calls (in Gentoo), but was unable to get anything to link
>>>> without mlong-calls when CONFIG_PARISC_PAGE_SIZE_16KB=y.
>>> I wouldn't recommend the above option.  It affects alignment of some things
>>> in kernel
>>> and as you found it makes the kernel bigger.  There are also some things in
>>> userspace
>>> that assume 4KB pages.
>> I expect we're past the point where there are any significant
>> obstacles to userspace support. Most platforms successfully support
>> multiple page sizes these days.
> But they don't have the problem we do with non equivalent aliasing. The data section starts on a
> page boundary on parisc and it doesn't overlap text.

I'd be astonished, if anything other than 4kB page size is able to 
boot to a login prompt.
For example, I know the parisc PCI-specific code (dino,lba,...) still
depends on 4kb page sizes.
I've left the CONFIG options in the source in the hope somebody
will try to finish >4kb page support at some point.


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