From: Danny Milosavljevic <dannym@scratchpost.org>
To: Jan Nieuwenhuizen <janneke@gnu.org>
Cc: guix-devel@gnu.org, tinycc-devel@nongnu.org,
Michael Matz <matz.tcc@frakked.de>,
Paul Sherwood <paul.sherwood@codethink.co.uk>,
bootstrappable@freelists.org
Subject: Re: [bootstrappable] Re: wip-full-source-bootstrap: from a 357-byte `hex0' to 'hello'
Date: Fri, 8 Jan 2021 14:43:47 +0100 [thread overview]
Message-ID: <20210108144347.12d82f90@scratchpost.org> (raw)
In-Reply-To: <87ble0ueq7.fsf@gnu.org>
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Hi Janneke,
On Fri, 08 Jan 2021 07:25:52 +0100
Jan Nieuwenhuizen <janneke@gnu.org> wrote:
> > Alignment could be disabled on the CPU
> >
> > https://developer.arm.com/documentation/ddi0464/f/system-control/register-descriptions/system-control-register
> >
> > but I don't think EABI wants that.
>
> Hmm, what does this mean? We are not really using EABI, or are we?
VFP is a floating point unit on ARM CPUs. It has been designed to either
require aligned members and be fast, or not, depending on a CPU flag that
for example the kernel can set.
See also https://www.keil.com/support/man/docs/armcc/armcc_chr1359124231926.htm
for much more detail.
ARM is a famously mix-and-match CPU, so the client can choose whatever
they want.
If you choose aligned-only, you will get a bus error on misaligned access.
A single program really shouldn't be choosing--it's more the entire platform
doing the choosing.
EABI has standardized on particular settings, among which is required alignment.
<https://www.keil.com/support/man/docs/armcc/armcc_chr1359124228744.htm>
> So alignment should be fixed, but that's more work and you propose a
> workaround, right?
No, I wanted to find out what's going on first.
Now that grischka commented and I looked up the malloc docs, I suggest
to fix mes libc's malloc to align what it gives back. That's all--that
should fix everything.
We should provide maxalign_t to make it known to the user what the
malloc alignment we are using is.
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next prev parent reply other threads:[~2021-01-08 13:44 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-04 17:01 wip-full-source-bootstrap: from a 357-byte `hex0' to 'hello' Jan Nieuwenhuizen
2021-01-05 0:49 ` [bootstrappable] " jeremiah
2021-01-05 16:58 ` Pierre Neidhardt
2021-01-06 11:32 ` [bootstrappable] " Ludovic Courtès
2021-01-06 11:46 ` [bootstrappable] " Andrius Štikonas via Development of GNU Guix and the GNU System distribution.
2021-01-06 14:03 ` Orians, Jeremiah (DTMB)
2021-01-14 21:37 ` Ludovic Courtès
2021-01-15 1:27 ` jeremiah
2021-01-21 11:09 ` Ludovic Courtès
2021-01-21 17:52 ` Orians, Jeremiah (DTMB)
2021-01-28 13:40 ` Ludovic Courtès
2021-01-28 13:44 ` Orians, Jeremiah (DTMB)
2021-01-06 14:38 ` [bootstrappable] " Paul Sherwood
2021-01-07 10:43 ` Jan Nieuwenhuizen
2021-01-07 20:10 ` [bootstrappable] " Danny Milosavljevic
2021-01-07 20:23 ` Danny Milosavljevic
2021-01-07 22:52 ` Danny Milosavljevic
2021-01-08 6:25 ` Jan Nieuwenhuizen
2021-01-08 8:05 ` [Tinycc-devel] " arnold
2021-01-08 13:02 ` Jan Nieuwenhuizen
2021-01-08 13:43 ` Danny Milosavljevic [this message]
2021-01-08 14:07 ` Danny Milosavljevic
2021-01-08 16:15 ` Jan Nieuwenhuizen
2021-01-08 18:56 ` Danny Milosavljevic
2021-01-08 21:11 ` Danny Milosavljevic
2021-01-08 22:13 ` Jan Nieuwenhuizen
2021-01-08 7:16 ` [Tinycc-devel] " grischka
2021-01-08 13:25 ` Danny Milosavljevic
2021-01-08 13:36 ` [bootstrappable] Re: [Tinycc-devel] " Orians, Jeremiah (DTMB)
2021-01-08 15:16 ` [Tinycc-devel] [bootstrappable] " Vincent Lefevre
2021-01-08 16:12 ` [Tinycc-devel] [bootstrappable] " Jan Nieuwenhuizen
2021-01-25 22:47 ` ARM Unified Assembly Language - GNU as does some weird stuff Danny Milosavljevic
2021-01-25 23:12 ` [bootstrappable] " Orians, Jeremiah (DTMB)
2021-01-26 1:14 ` Danny Milosavljevic
2021-01-08 0:29 ` wip-full-source-bootstrap: from a 357-byte `hex0' to 'hello' Jan Wielkiewicz
2021-01-20 20:19 ` Timothy Sample
2021-01-25 18:48 ` Efraim Flashner
2021-01-29 7:23 ` [bootstrappable] " Jan Nieuwenhuizen
2021-01-29 10:18 ` andrius--- via Development of GNU Guix and the GNU System distribution.
2021-01-29 16:02 ` Orians, Jeremiah (DTMB)
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