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From: Simon Marchi <simark@simark.ca>
To: John Baldwin <jhb@FreeBSD.org>, gdb-patches@sourceware.org
Subject: Re: [PATCH 1/9] Support the fs_base and gs_base registers on i386.
Date: Sun, 27 Jan 2019 04:22:00 -0000	[thread overview]
Message-ID: <5c89f494-c6a9-37fc-bfdf-954d27f0f026@simark.ca> (raw)
In-Reply-To: <afb3f5e132cc8844216f7da3084b2db9ddf73d14.1548180889.git.jhb@FreeBSD.org>

On 2019-01-22 1:42 p.m., John Baldwin wrote:
> As on amd64, these registers hold the base address of the fs and gs
> segments, respectively.  For i386 these two registers are 32 bits.

I just started to look at this, still trying to get my head around it and
connect all the dots.  Just a silly question for now:

> diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
> index d4143ae155..1eb0bcdf17 100644
> --- a/gdb/amd64-tdep.c
> +++ b/gdb/amd64-tdep.c
> @@ -3107,15 +3107,7 @@ amd64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch,
>  
>    if (tdesc_find_feature (tdesc, "org.gnu.gdb.i386.segments") != NULL)
>      {
> -      const struct tdesc_feature *feature =
> -	  tdesc_find_feature (tdesc, "org.gnu.gdb.i386.segments");
> -      struct tdesc_arch_data *tdesc_data_segments =
> -	  (struct tdesc_arch_data *) info.tdep_info;
> -
> -      tdesc_numbered_register (feature, tdesc_data_segments,
> -		       AMD64_FSBASE_REGNUM, "fs_base");
> -      tdesc_numbered_register (feature, tdesc_data_segments,
> -		       AMD64_GSBASE_REGNUM, "gs_base");
> +      tdep->fsbase_regnum = AMD64_FSBASE_REGNUM;
>      }

Can you explain what this change does and why it is needed?  I am a bit lost.

I see you add something equivalent in i386-tdep.c, but as far as I know, they are completely
separate.

Simon


  reply	other threads:[~2019-01-27  4:22 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-22 18:43 [PATCH 0/9] Support for thread-local variables on FreeBSD John Baldwin
2019-01-22 18:43 ` [PATCH 7/9] Support TLS variables on FreeBSD/i386 John Baldwin
2019-01-22 18:43 ` [PATCH 9/9] Support TLS variables on FreeBSD/powerpc John Baldwin
2019-01-22 18:43 ` [PATCH 1/9] Support the fs_base and gs_base registers on i386 John Baldwin
2019-01-27  4:22   ` Simon Marchi [this message]
2019-01-28 17:54     ` John Baldwin
2019-02-02 15:11       ` Simon Marchi
2019-01-22 18:43 ` [PATCH 3/9] Handle TLS variable lookups when using separate debug object files John Baldwin
2019-02-02 15:52   ` Simon Marchi
2019-02-04 20:02     ` John Baldwin
2019-02-05 20:06       ` Simon Marchi
2019-02-05 22:21         ` John Baldwin
2019-02-05 22:33           ` John Baldwin
     [not found]             ` <67973931006085a171ad69952649de33@polymtl.ca>
2019-02-07  4:08               ` Simon Marchi
2019-01-22 18:43 ` [PATCH 6/9] Support TLS variables on FreeBSD/amd64 John Baldwin
2019-01-22 18:43 ` [PATCH 2/9] Support fs_base and gs_base on FreeBSD/i386 John Baldwin
2019-02-02 15:26   ` Simon Marchi
2019-02-04 19:45     ` John Baldwin
2019-02-05 18:59       ` Simon Marchi
2019-01-22 18:52 ` [PATCH 8/9] Support TLS variables on FreeBSD/riscv John Baldwin
2019-01-27 23:35   ` Andrew Burgess
2019-01-22 18:52 ` [PATCH 4/9] Add a new gdbarch method to resolve the address of TLS variables John Baldwin
2019-01-22 18:52 ` [PATCH 5/9] Add a helper function to resolve TLS variable addresses for FreeBSD John Baldwin
2019-01-24 17:09   ` John Baldwin
2019-02-07  5:05     ` Simon Marchi
2019-02-07 17:02       ` John Baldwin
2019-02-09  0:34         ` John Baldwin

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