Re: [PATCH 14/17] [PowerPC] Add gdbserver support for HTM registers

["Ulrich Weigand" <uweigand@de.ibm.com>]

Pedro Franco de Carvalho wrote:

> The "fill" functions for checkpointed register sets are not
> implemented, because ptrace can return ENODATA for these regsets
> whenever the inferior is not in a transaction.
> 
> Since gdbserver writes all registers in one go before resuming the
> inferior, this error would not be detected at the time the user tries
> to write to one of the registers on the client side, and gdbserver
> would print out warnings every time it resumes the inferior when it is
> not in a transaction, so there is currently no straightforward way to
> handle this case. This means the checkpointed registers in the
> client-side regcache can become dirty when the user tries to write to
> them, until the inferior is resumed and stopped again.
> 
> Another limitation for the checkpointed registers is that traceframes
> don't record if registers are available or not, so if these registers
> are collected when a tracepoint is hit and the inferior is not in a
> transaction, the user will see zero values for all of them, instead of
> the usual <unavailable>.

Hmm.  It's a bit unfortunate to have these differences between native
and gdbserver debugging.  But I guess this is unavoidable for now.

> gdb/gdbserver/ChangeLog:
> 2018-07-05  Pedro Franco de Carvalho  <pedromfc@linux.ibm.com>
> 
> 	* linux-ppc-tdesc-init.h (enum ppc_linux_tdesc)
> 	<PPC_TDESC_ISA207_HTM_VSX>: New enum value.
> 	(init_registers_powerpc_isa207_htm_vsx32l)
> 	(init_registers_powerpc_isa207_htm_vsx64l): Declare.
> 	* linux-ppc-low.c (ppc_fill_tm_sprregset, ppc_store_tm_sprregset)
> 	(ppc_store_tm_cgprregset, ppc_store_tm_cfprregset)
> 	(ppc_store_tm_cvrregset, ppc_store_tm_cvsxregset)
> 	(ppc_store_tm_cpprregset, ppc_store_tm_cdscrregset)
> 	(ppc_store_tm_ctarregset): New functions.
> 	(ppc_regsets): Add entries for HTM regsets.
> 	(ppc_arch_setup): Set htm in features struct when needed. Set
> 	sizes for the HTM regsets.
> 	(ppc_get_ipa_tdesc_idx): Return PPC_TDESC_ISA207_HTM_VSX.
> 	(initialize_low_arch): Call
> 	init_registers_powerpc_isa207_htm_vsx32l and
> 	init_registers_powerpc_isa207_htm_vsx64l.
> 	* linux-ppc-ipa.c (get_ipa_tdesc): Handle
> 	PPC_TDESC_ISA207_HTM_VSX.
> 	(initialize_low_tracepoint): Call
> 	init_registers_powerpc_isa207_htm_vsx32l and
> 	init_registers_powerpc_isa207_htm_vsx64l.

This is OK once base support is in.

Thanks,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU/Linux compilers and toolchain
  Ulrich.Weigand@de.ibm.com