Re: [PATCH] target/ppc: Fix BookE debug interrupt generation

[Fabiano Rosas <farosas@linux.ibm.com>]

Bin Meng <bmeng.cn@gmail.com> writes:

> On Wed, Apr 20, 2022 at 9:50 PM Fabiano Rosas <farosas@linux.ibm.com> wrote:
>>
>> Bin Meng <bmeng.cn@gmail.com> writes:
>>
>> > From: Bin Meng <bin.meng@windriver.com>
>> >
>> > Per PowerISA v2.07 [1], Book III-E, chapter 7.6 "Interrupt definitions"
>>
>> Which BookE board are you concerned about? I don't think we have any
>> BookE ISA v2.07 in QEMU currently.
>
> It's actually a PPC E500 core, but I am too lazy to dig out the E500
> manual from Freescale/NXP :(

Here it is: https://www.nxp.com/docs/en/reference-manual/E500CORERM.pdf

You can keep it =)

> Let me know if I need to replace the link to an E500 manual.

Yes, please. And the description as well:

  "An instruction complete debug event occurs when any instruction
  completes execution so long as MSR[DE] and DBCR0[ICMP] are both set..."
  
  "Instruction complete debug events are not recognized if MSR[DE] is
  cleared at the time of the instruction execution."

Otherwise a few years from now someone will use the git log as reference
and will get confused.

Thanks.

>>
>> > "When in Internal Debug Mode with MSR.DE=0, then Instruction Complete
>> > and Branch Taken debug events cannot occur, and no DBSR status bits
>> > are set and no subsequent imprecise Debug interrupt will occur."
>> >
>> > Current codes do not check MSR.DE bit before setting HFLAGS_SE and
>> > HFLAGS_BE flag, which would cause the immediate debug interrupt to
>> > be generated, e.g.: when DBCR0.ICMP bit is set by guest software
>> > and MSR.DE is not set.
>> >
>>
>> The rationale and the change itself look ok.
>>
>> > [1] https://ibm.ent.box.com/s/jd5w15gz301s5b5dt375mshpq9c3lh4u
>> >
>> > Signed-off-by: Bin Meng <bin.meng@windriver.com>
>> > ---
>> >
>> >  target/ppc/helper_regs.c | 4 ++--
>> >  1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>
> Regards,
> Bin