From: Tom de Vries <tdevries@suse.de>
To: Mark Wielaard <mark@klomp.org>
Cc: dwz@sourceware.org, jakub@redhat.com, Michael Matz <matz@suse.de>
Subject: Re: [PATCH] Add -p native and -e native
Date: Fri, 9 Apr 2021 14:48:18 +0200 [thread overview]
Message-ID: <2cc8f90d-ec0a-bd8c-f8b8-92643dbd9dbe@suse.de> (raw)
In-Reply-To: <20210409094231.GD30119@wildebeest.org>
[-- Attachment #1: Type: text/plain, Size: 1850 bytes --]
On 4/9/21 11:42 AM, Mark Wielaard wrote:
> On Fri, Apr 09, 2021 at 11:24:41AM +0200, Tom de Vries wrote:
>> Add option parameter native to options -p and -e.
>>
>> We determine native as the result of:
>> - -p: sizeof (void *)
>> - -e: __BYTE_ORDER__
>> when compiling using CC without CFLAGS, such that if we build dwz with -m32 on
>> x86_64 like so:
>> ...
>> $ make CFLAGS="-m32 -O2 -g" LDFLAGS=-m32
>> ...
>> and we have:
>> ...
>> $ file ./dwz
>> dwz: ELF 32-bit LSB executable, Intel 80386 <SNIP>
>> ...
>> we still have:
>> ...
>> $ ./dwz -?
>> ...
>> -p, --multifile-pointer-size <SIZE|auto|native>
>> Set pointer size of multifile, in number of bytes.
>> Native pointer size is 8.
>> Default value: auto.
>> ...
>>
>> Any comments?
>
> Except for this narrow multilib case, doesn't this actually make it
> impossible to do a cross-arch build?
I think so, yes. If say we'd have a cross compiler targeting arm but
running on x86_64, then the ./native exec would be for arm but we'd try
to run it on x86_64.
> I don't think this should be a
> compile time option, unless it can derived from the target
> architecture that the dwz binary is build for.
I have an updated patch that does that, AFAIU.
I just wonder whether using the term native for this functionality will
cause confusion. Perhaps 'self' is a better way of describing this?
And now I also wonder about whether there are architectures where using
__SIZEOF_POINTER__ will be different than what is generated as dwarf
pointer size. If so, in the previous setup I could have used CC -g,
readelf and grep to find out what is actually used and pass that as a
define to args.c
Perhaps it's a mistake to try to assign any functionality to 'native'
when crosscompiling.
Thanks,
- Tom
[-- Attachment #2: 0001-Add-p-native-and-e-native.patch --]
[-- Type: text/x-patch, Size: 4714 bytes --]
Add -p native and -e native
Add option parameter native to options -p and -e.
We determine native as the result of:
- -p: __SIZEOF_POINTER__
- -e: __BYTE_ORDER__
in dwz.
2021-04-09 Tom de Vries <tdevries@suse.de>
* args.c (XSTR, STR, NATIVE_ENDIAN_STRING): New macro.
(dwz_multi_file_options_help, usage): Mention -p native and -e native.
(parse_args): Handle -p native and -e native.
* dwz.1 (-p, -e): Mention native.
---
args.c | 42 +++++++++++++++++++++++++++++++++++++-----
dwz.1 | 10 ++++++----
2 files changed, 43 insertions(+), 9 deletions(-)
diff --git a/args.c b/args.c
index 23bf1d4..5a664cf 100644
--- a/args.c
+++ b/args.c
@@ -32,6 +32,8 @@
#include "args.h"
#define IMPLIES(A, B) (!((A) && !(B)))
+#define XSTR(s) STR(s)
+#define STR(s) #s
#if DEVEL
int tracing;
@@ -220,6 +222,14 @@ static struct option_help dwz_single_file_options_help[] =
"Place the output in OUTFILE." }
};
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define NATIVE_ENDIAN_STRING little
+#elif NATIVE_ENDIAN == __ORDER_BIG_ENDIAN__
+#define NATIVE_ENDIAN_STRING big
+#else
+#define NATIVE_ENDIAN_STRING not available
+#endif
+
/* Describe mult-file command line options. */
static struct option_help dwz_multi_file_options_help[] =
{
@@ -236,10 +246,12 @@ static struct option_help dwz_multi_file_options_help[] =
{ "5", "dwarf-5", NULL, NULL,
"Emit DWARF 5 standardized supplementary object files instead of"
" GNU extension .debug_altlink." },
- { "p", "multifile-pointer-size", "<SIZE|auto>", "auto",
- "Set pointer size of multifile, in number of bytes." },
- { "e", "multifile-endian", "<l|b|auto>", "auto",
- "Set endianity of multifile." },
+ { "p", "multifile-pointer-size", "<SIZE|auto|native>", "auto",
+ "Set pointer size of multifile, in number of bytes."
+ " Native pointer size is " XSTR (__SIZEOF_POINTER__) "." },
+ { "e", "multifile-endian", "<l|b|auto|native>", "auto",
+ "Set endianity of multifile."
+ " Native endianity is " XSTR (NATIVE_ENDIAN_STRING) "." },
{ "j", "jobs", "<n>", "number of processors / 2",
"Process <n> files in parallel." }
};
@@ -385,7 +397,7 @@ usage (int failing)
FILE *stream = failing ? stderr : stdout;
const char *header_lines[] = {
"dwz [common options] [-h] [-m COMMONFILE] [-M NAME | -r] [-5]",
- " [-p <SIZE|auto>] [-e <l|b|auto>] [-j N] [FILES]",
+ " [-p <SIZE|auto|native>] [-e <l|b|auto|native>] [-j N] [FILES]",
"dwz [common options] -o OUTFILE FILE",
"dwz [ -v | -? ]"
};
@@ -650,6 +662,11 @@ parse_args (int argc, char *argv[], bool *hardlink, const char **outfile)
multifile_force_ptr_size = 0;
break;
}
+ if (strcmp (optarg, "native") == 0)
+ {
+ multifile_force_ptr_size = __SIZEOF_POINTER__;
+ break;
+ }
l = strtoul (optarg, &end, 0);
if (*end != '\0' || optarg == end || (unsigned int) l != l)
error (1, 0, "invalid argument -l %s", optarg);
@@ -662,6 +679,21 @@ parse_args (int argc, char *argv[], bool *hardlink, const char **outfile)
multifile_force_endian = 0;
break;
}
+ if (strcmp (optarg, "native") == 0)
+ {
+ switch (__BYTE_ORDER__)
+ {
+ case __ORDER_LITTLE_ENDIAN__:
+ multifile_force_endian = ELFDATA2LSB;
+ break;
+ case __ORDER_BIG_ENDIAN__:
+ multifile_force_endian = ELFDATA2MSB;
+ break;
+ default:
+ error (1, 0, "Cannot determine native endian");
+ }
+ break;
+ }
if (strlen (optarg) != 1)
error (1, 0, "invalid argument -l %s", optarg);
switch (optarg[0])
diff --git a/dwz.1 b/dwz.1
index 6fec6ed..1cff329 100644
--- a/dwz.1
+++ b/dwz.1
@@ -77,13 +77,15 @@ the executable or shared library to the file named in the argument
of the \fB-m\fR option. Either \fB-M\fR or \fB-r\fR
option can be specified, but not both.
.TP
-.B \-p N \-\-multifile-pointer-size <N|auto>
+.B \-p N \-\-multifile-pointer-size <N|auto|native>
Specify the pointer size of the multifile, in bytes. If auto, use the
-pointer size of the files, provided they match.
+pointer size of the files, provided they match. If native, use native pointer
+size, as specified in the help message.
.TP
-.B \-p <l|b|auto> \-\-multifile-endian <l|b|auto>
+.B \-p <l|b|auto> \-\-multifile-endian <l|b|auto|native>
Specify the endianity of the multifile. If auto, use the endianity of
-the files, provided they match.
+the files, provided they match. If native, use native endianity, as specified
+in the help message.
.TP
.B \-q \-\-quiet
Silence up some of the most common messages.
next prev parent reply other threads:[~2021-04-09 12:48 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-09 9:24 Tom de Vries
2021-04-09 9:42 ` Mark Wielaard
2021-04-09 12:48 ` Tom de Vries [this message]
2021-04-09 13:03 ` Michael Matz
2021-04-09 15:58 ` Tom de Vries
2021-04-12 12:33 ` Michael Matz
2021-04-12 15:11 ` Tom de Vries
2021-04-12 19:53 ` [committed] " Tom de Vries
2021-04-12 20:14 ` [PATCH] " Mark Wielaard
2021-04-13 7:45 ` Tom de Vries
2021-04-13 8:33 ` Tom de Vries
2021-04-13 10:04 ` Mark Wielaard
2021-04-13 11:15 ` Tom de Vries
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