# Re: \[PATCH v2 1/2\] powerpc/hw\_breakpoints: Rewrite 8xx breakpoints to allow any address range size.

- From: Michael Ellerman \<hidden\>
- Date: 2020-01-29 05:17:32 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2020/01/5846656
- Thread: https://ratatoskr.run/linuxppc-dev/2019/11/5788621/t.md

```text
On Tue, 2019-11-26 at 17:43:29 UTC, Christophe Leroy wrote:
> Unlike standard powerpc, Powerpc 8xx doesn't have SPRN_DABR, but
> it has a breakpoint support based on a set of comparators which
> allow more flexibility.
> 
> Commit 4ad8622dc548 ("powerpc/8xx: Implement hw_breakpoint")
> implemented breakpoints by emulating the DABR behaviour. It did
> this by setting one comparator the match 4 bytes at breakpoint address
> and the other comparator to match 4 bytes at breakpoint address + 4.
> 
> Rewrite 8xx hw_breakpoint to make breakpoints match all addresses
> defined by the breakpoint address and length by making full use of
> comparators.
> 
> Now, comparator E is set to match any address greater than breakpoint
> address minus one. Comparator F is set to match any address lower than
> breakpoint address plus breakpoint length. Addresses are aligned
> to 32 bits.
> 
> When the breakpoint range starts at address 0, the breakpoint is set
> to match comparator F only. When the breakpoint range end at address
> 0xffffffff, the breakpoint is set to match comparator E only.
> Otherwise the breakpoint is set to match comparator E and F.
> 
> At the same time, use registers bit names instead of hardcoded values.
> 
> Signed-off-by: Christophe Leroy <redacted>
> Cc: Ravi Bangoria <redacted>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/39413ae009674c6ba745850515b551bbb9d6374b

cheers
```