Hi, Ling Kun:
Glad to hear loongson team has solved this issue! I googled this feature
on gnu site, I do not find the relevant documents. Could you please write
some documents or elaborate more on your patch?
Thanks a lot!
Regards
Gang
2012/1/1 凌坤 <erlv5...@gmail.com>
> Hi, Sun:
> I am glad to do that. And now I am trying to merge this patch to Open64
> svn trunck, it is a little complex to try to pick it from the Loongson
> branch :)
> Hoping that a patch that can pass some testcase can be submit in 1-2
> days :)
>
> Happy New year.
>
> Ling Kun
> **
>
>
> ------------------ Original ------------------
> *From: * "Sun Chan"<sun.c...@gmail.com>;
> *Date: * Sun, Jan 1, 2012 02:25 PM
> *To: * "Ling Kun"<lkun.e...@gmail.com>; **
> *Cc: * "open64-devel"<open64-devel@lists.sourceforge.net>; **
> *Subject: * Re: [Open64-devel] Current build status for linux kernel on
> open64
>
> LingKun,
>
> can you send the changes for VLS (or VLA) to this alias (or send to me
> and Yugang privately and we can help review and test out on x86) for
> review?
> Sun
>
> On Sun, Jan 1, 2012 at 10:14 AM, Ling Kun <lkun.e...@gmail.com> wrote:
> > hi, Gang Yu:
> > Loongson compiler(based on Open64) team have successfully build MIPS
> > Linux kernel 2.6.35, and make it run on Qemu. And we have solved the VLA
> > issue, the debug record and patches (based on the Open64 trunck svn
> r28xx)
> > of Loongson teams' work have be sent to Zhu qing.
> > If it is possible, we are glad to merge our VLA work to Open64 current
> > SVN trunck version.
> >
> > Ling Kun.
> >
> >
> >
> > On Sat, Dec 31, 2011 at 10:45 AM, Gang Yu <yugang...@gmail.com> wrote:
> >>
> >> Thanks. we also wish could get input from the original wgen authors, it
> is
> >> leaving an unsupported feature for VLA and then compiler asserts. In
> order
> >> to avoid duplication of effort, we wish learn from the seniors and then
> we
> >> can go ahead or make workaround.
> >>
> >>
> >> Regards
> >> Gang
> >>
> >>
> >>
> >> On Sat, Dec 31, 2011 at 10:42 AM, Sun Chan <sun.c...@gmail.com> wrote:
> >>>
> >>> Let me try to understand. You are asking for opinions on whether ope64
> >>> should ignore the VLA problem until there is further documentation
> >>> and/or evidence of more VLA usage? Until then, workaround that by
> >>> changing kernel source?
> >>> Sun
> >>>
> >>> On Sat, Dec 31, 2011 at 10:36 AM, Gang Yu <yugang...@gmail.com> wrote:
> >>> > Hi, list:
> >>> >
> >>> > We have some efforts on building and tuning linux kernel on open64,
> >>> > we
> >>> > have fixed several bugs and now we have only two building issues and
> >>> > several running issues at x86_64 target, O2 level.
> >>> >
> >>> > linux 2.6.32 as an example, the two building issues are:
> >>> >
> >>> > A). bug787, Rao Shivarama has submitted a patch, but due to the
> >>> > regression
> >>> > filed as bug882, the patch is backed out. This is still a pending
> >>> > issue. My
> >>> > personally investigation shows Rao's approach is on the right track,
> >>> > the
> >>> > bug882 shows the fix triggers the SSA version verification issues
> which
> >>> > are
> >>> > already known in open64, filed as bug889/891/892. We will continue
> work
> >>> > on
> >>> > it.
> >>> >
> >>> > B). the Variable Length Array in Structs (VLAS), this is a common
> issue
> >>> > for
> >>> > non-gnu compilers.
> >>> >
> >>> > clang documents the issue below:
> >>> >
> >>> > Intentionally unsupported GCC extensions
> >>> >
> >>> > clang does not support the gcc extension that allows variable-length
> >>> > arrays
> >>> > in structures. This is for a few reasons: one, it is tricky to
> >>> > implement,
> >>> > two, the extension is completely undocumented, and three, the
> extension
> >>> > appears to be rarely used. Note that clang does support flexible
> array
> >>> > members (arrays with a zero or unspecified size at the end of a
> >>> > structure).
> >>> >
> >>> >
> >>> > I review the failure case of kernel build, the VLAS are not the
> >>> > flexible
> >>> > array members(case like this : struct A { int a; int b; char ctx[]}
> is
> >>> > called Flexible array menbers. It is a newly introduced feature c99
> or
> >>> > later, open64 supports it well.)
> >>> >
> >>> > VLAS does not appear in linux kernel source code frequently:
> >>> >
> >>> > lib/libcrc32c.c
> >>> > u32 crc32c(u32 crc, const void *address, unsigned int length)
> >>> > 43{
> >>> > 44 struct {
> >>> > 45 struct shash_desc shash;
> >>> > 46 char ctx[crypto_shash_descsize(tfm)];
> >>> > 47 } desc;
> >>> > crypto/testmgr.c
> >>> > struct {
> >>> > 1432 struct shash_desc shash;
> >>> > 1433 char ctx[crypto_shash_descsize(tfm)];
> >>> > 1434 } sdesc;
> >>> > crypo/hmac.c
> >>> > struct {
> >>> > 1432 struct shash_desc shash;
> >>> > 1433 char ctx[crypto_shash_descsize(tfm)
> >>> > ];
> >>> > 1434 } sdesc;
> >>> >
> >>> >
> >>> > I just speculate that clang will support kernel build by flexible
> >>> > array
> >>> > members. It is not the case,
> >>> >
> >>> > http://llvm.org/bugs/show_bug.cgi?id=4071
> >>> >
> >>> > and people claim that they build up kernel with clang, but it is not
> >>> > fully
> >>> > functional.
> >>> >
> >>> > http://lists.cs.uiuc.edu/pipermail/cfe-dev/2010-October/011711.html
> >>> >
> >>> > as this guy pointed out,
> >>> >
> >>> > * SELinux, Posix ACLs, IPSec, eCrypt, anything that uses the crypto
> >>> > API -
> >>> > None
> >>> > of these will compile, due to either an ICE or variable-length
> >>> > arrays in
> >>> > structures (don't remember which, it's in my notes somewhere). If
> >>> > it's
> >>> > variable-length arrays or another intentionally unsupported
> >>> > GNUtension,
> >>> > I'm
> >>> > hoping it's just used in some isolated implementation detail (or
> >>> > details),
> >>> > and not a fundamental part of the crypto API (honestly just haven't
> >>> > had
> >>> > a
> >>> > chance to dive into the crypto source yet). I'm really hoping it's
> >>> > an
> >>> > issue
> >>> > in Clang, though, as it's easier for me to hack Clang and I'm
> >>> > trying to
> >>> > avoid kernel patches as much as possible.
> >>> >
> >>> >
> >>> > We meet the problem and post it out, we wish we could get input from
> >>> > community and go on the kernel building/tuning work to broaden the
> >>> > open64's
> >>> > application and improve the code quality.
> >>> >
> >>> > Thanks.
> >>> >
> >>> > Regards
> >>> > Gang
> >>> >
> >>> >
> >>> >
> ------------------------------------------------------------------------------
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> >>> > https://lists.sourceforge.net/lists/listinfo/open64-devel
> >>> >
> >>
> >>
> >>
> >>
> >>
> ------------------------------------------------------------------------------
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> >>
> >
> >
> >
> > --
> > http://www.lingcc.com
> >
> >
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> >
>
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