Date: Mon, 21 Jul 2014 08:46:49 -0600 From: Warner Losh <imp@bsdimp.com> To: John-Mark Gurney <jmg@funkthat.com> Cc: Tim Kientzle <tim@kientzle.com>, freebsd-arm <freebsd-arm@freebsd.org>, Fabien Thomas <fabient@freebsd.org>, Ian Lepore <ian@freebsd.org>, arch@freebsd.org Subject: Re: [CFR] mge driver / elf reloc Message-ID: <9464C309-B390-4A27-981A-E854921B1C98@bsdimp.com> In-Reply-To: <20140720231056.GQ45513@funkthat.com> References: <14D22EA6-B73C-47BA-9A86-A957D24F23B8@freebsd.org> <1405810447.85788.41.camel@revolution.hippie.lan> <20140720220514.GP45513@funkthat.com> <F6D53A17-FED0-4F08-BB5B-9F66C5AF5EF6@kientzle.com> <20140720231056.GQ45513@funkthat.com>
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On Jul 20, 2014, at 5:10 PM, John-Mark Gurney <jmg@funkthat.com> wrote:
> Tim Kientzle wrote this message on Sun, Jul 20, 2014 at 15:25 -0700:
>>=20
>> On Jul 20, 2014, at 3:05 PM, John-Mark Gurney <jmg@funkthat.com> =
wrote:
>>=20
>>> Ian Lepore wrote this message on Sat, Jul 19, 2014 at 16:54 -0600:
>>>> Sorry to take so long to reply to this, I'm trying to get caught =
up. I
>>>> see you've already committed the mge fixes. I think the ELF =
alignment
>>>> fix looks good and should also be committed.
>>>=20
>>> So, re the elf alignment...
>>>=20
>>> I think we should get a set of macros that handle load/stores =
to/from
>>> unaligned addresses that are transparent to the caller.... I need
>>> these for some other code I'm writing...=20
>>>=20
>>> I thought Open/Net had these available, but I can't seem to find =
them
>>> right now...
>>=20
>> $ man 9 byteorder
>>=20
>> is most of what you want, lacking only some aliases to pick
>> the correct macro for native byte order.
>=20
> Um, those doesn't help if you want native endian order=85
Ummm, yes they do. enc converts from native order. dec decodes to native =
byte
order. They are more general cases than the ntoh* functions that are =
more traditional
since they also work on byte streams that may not be completely aligned =
when
sitting in memory. Which is what you are asking for.
> Also, only the enc/dec functions are documented to work on non-aligned
> address, so that doesn't help in most cases=85
They work on all addresses. They are even documented to work on any =
address:
The be16enc(), be16dec(), be32enc(), be32dec(), be64enc(), =
be64dec(),
le16enc(), le16dec(), le32enc(), le32dec(), le64enc(), and =
le64dec()
functions encode and decode integers to/from byte strings on any =
align-
ment in big/little endian format.
So they are quite useful in general. Peeking under the covers at the =
implementation
also shows they will work for any alignment, so I=92m having trouble =
understanding
where this objection is really coming from.
Warner
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