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Re: [PATCH] Remove ioperm etc. support for arm
- From: Phil Blundell <pb at pbcl dot net>
- To: Florian Weimer <fweimer at redhat dot com>
- Cc: Aaro Koskinen <aaro dot koskinen at iki dot fi>, libc-alpha at sourceware dot org
- Date: Wed, 26 Jun 2019 17:00:53 +0200
- Subject: Re: [PATCH] Remove ioperm etc. support for arm
- References: <20190529135135.rt3c5fhhser7fik6@hetzner.pbcl.net> <875zptqrwx.fsf@oldenburg2.str.redhat.com> <20190529141820.5nny64ugrvqyzqgd@hetzner.pbcl.net> <87r28hpb0l.fsf_-_@oldenburg2.str.redhat.com> <20190529184028.GC24195@darkstar.musicnaut.iki.fi> <87ef4hp08c.fsf@oldenburg2.str.redhat.com> <20190529201227.GD24195@darkstar.musicnaut.iki.fi> <87imttnewj.fsf@oldenburg2.str.redhat.com> <20190606215312.GB11598@darkstar.musicnaut.iki.fi> <87d0j0lap3.fsf@oldenburg2.str.redhat.com>
On Wed, Jun 26, 2019 at 03:48:08PM +0200, Florian Weimer wrote:
> * Aaro Koskinen:
> > Just building with -march=armv4t should be enough for a start.
>
> This architecture doesn't have its own target triplet, right?
Right. You can configure with "armv4t-unknown-linuxgnueabi" if
you like but I don't think the glibc configury does anything
different for "armv4t" than for plain "arm".
> With the patch below, I get this in csu/init-first.os:
>
> 00000000 <__libc_init_first>:
> 0: e12fff1e bx lr
> 0: R_ARM_V4BX *ABS*
>
> But after linking, get this in libc.so.6:
>
> 000175a0 <__libc_init_first>:
> 175a0: e12fff1e bx lr
>
> Does this mean I need to pass some other flags as well?
No, that looks about right. ARMv4T does have "bx rN" so it
is OK for that instruction to be generated. You might be
thinking of ARMv4, which doesn't have bx at all and needs
the linker to patch them (gcc passes --fix-v4bx from its
specs when building for ARMv4) or the "blx" instruction
which is only in ARMv5T and upwards.
p.