[PATCH] RISC-V: Resurrect the MMIO timer implementation for M-mode systems

[Atish Patra]

On Tue, Sep 15, 2020 at 12:02 AM Damien Le Moal <Damien.LeMoal at wdc.com> wrote:
>
> On 2020/09/15 15:51, hch at infradead.org wrote:
> > On Tue, Sep 15, 2020 at 06:50:24AM +0000, Damien Le Moal wrote:
> >> On 2020/09/15 14:47, Christoph Hellwig wrote:
> >>> I won't have time to set up the K210, but this fixes the timer issues
> >>> on older Qemu versions that don't implement the time CSR.  Although I
> >>> also need to revert the binfmt_flat patch to actually get to userspace.
> >>
> >> So revert is needed ? Digging in the flatbin format, I do not see why the offset
> >> you removed would be needed, and it does not seem to affect other arch anyway.
> >> So I am really suspecting a problem with riscv uclibcb or elf2flt, but can't
> >> quite yet figure out what may be wrong there.
> >
> > I did not have time to find out if what we did in RISC-V nommu was
> > correct or wrong.  But to get my existing userspace to work I had to
> > revert the revert.  I'll try to find some time to dig into the binfmt
> > flat issue and elf2flt soon.
>
> OK. Thanks. I will keep digging too when I have time.
>

Is there a solution to this ? As Christoph pointed out, we need to
revert the revert to get into user space for nommu kernel (v5.9 or
v5.10-rc1).
This commit was introduced between 5.9-rc2 & 5.9-rc3.

The concerned commit here is:
2217b982624680d19a80ebb4600d05c8586c4f96: binfmt_flat: revert
"binfmt_flat: don't offset the data start"

>
>
> --
> Damien Le Moal
> Western Digital Research
>
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-- 
Regards,
Atish