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Old 11-17-2010, 09:36 AM
nodata
 
Default Fixing the glibc adobe flash incompatibility

On 17/11/10 10:20, drago01 wrote:
> On Wed, Nov 17, 2010 at 10:17 AM, nodata<lsof@nodata.co.uk> wrote:
>> On 17/11/10 08:57, Hans de Goede wrote:
>>> Hi all,
>>>
>>> For those who do not know it yet, recent Fedora glibc updates include
>>> an optimized memcpy (which gets used on some processors) which breaks the
>>> 64 bit adobe flash plugin.
>>>
>>> The problem has been analyzed and is known, as well as a fix for it, see:
>>> https://bugzilla.redhat.com/show_bug.cgi?id=638477
>>>
>>> The problem still exists however. The glibc developers say that this is
>>> not a glibc bug, but a flash plugin bug. And technically they are 100%
>>> correct, and the adobe flash plugin is a buggy .... (no surprise there).
>>> To be specific the flash plugin is doing overlapping memcpy-s which is
>>> clearly not how memcpy is supposed to be used. But the way the flash
>>> plugin does overlapping memcpy's happens to work fine as long as one as
>>> the c library does the memcpy-s in forward direction. And the new memcpy
>>> implementation does the memcpy in backward direction.
>>>
>>> The glibc developers being technically 100% correct is not helping our
>>> end users in this case though. So we (The Fedora project) need to come up
>>> with a solution to help our end users, many of whom want to use the adobe
>>> flash plugin.
>>>
>>> This solution could be reverting the problem causing glibc change, or
>>> maybe changing it to do forward memcpy's while still using the new SSE
>>> instructions, or something more specific to the flash plugin, as long
>>> as it will automatically fix things with a yum upgrade without requiring
>>> any further user intervention.
>>>
>>> I would also like to point out that if this were to happen in Ubuntu
>>> which we sometimes look at jealously for getting more attention / users
>>> then us, the glibc change would likely be reverted immediately, as that
>>> is the right thing to do from an end user pov.
>>>
>>> I've filed a ticket for FESCo to look into this, as I believe this
>>> makes us look really bad, and the glibc maintainers do not seem to be
>>> willing to fix it without some sort of intervention:
>>> https://fedorahosted.org/fesco/ticket/501
>>>
>>> Regards,
>>>
>>> Hans
>>
>> Is someone talking to Adobe about this?
>
> Yes, see https://bugs.adobe.com/jira/browse/FP-5739

Adobe benefits from Flash in Linux. So it seems sensible to:

1. Get Adobe to commit to a fix soon WITH A $DATE
2. Agree to patch the change until $DATE
3. Adobe updates Flash, we revert the patch, everyone is happy
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Old 11-17-2010, 02:17 PM
Magnus Glantz
 
Default Fixing the glibc adobe flash incompatibility

On 11/17/2010 11:36 AM, nodata wrote:
> On 17/11/10 10:20, drago01 wrote:
>> On Wed, Nov 17, 2010 at 10:17 AM, nodata<lsof@nodata.co.uk> wrote:
>>> On 17/11/10 08:57, Hans de Goede wrote:
>>>> Hi all,
>>>>
>>>> For those who do not know it yet, recent Fedora glibc updates include
>>>> an optimized memcpy (which gets used on some processors) which breaks the
>>>> 64 bit adobe flash plugin.
>>>>
>>>> The problem has been analyzed and is known, as well as a fix for it, see:
>>>> https://bugzilla.redhat.com/show_bug.cgi?id=638477
>>>>
>>>> The problem still exists however. The glibc developers say that this is
>>>> not a glibc bug, but a flash plugin bug. And technically they are 100%
>>>> correct, and the adobe flash plugin is a buggy .... (no surprise there).
>>>> To be specific the flash plugin is doing overlapping memcpy-s which is
>>>> clearly not how memcpy is supposed to be used. But the way the flash
>>>> plugin does overlapping memcpy's happens to work fine as long as one as
>>>> the c library does the memcpy-s in forward direction. And the new memcpy
>>>> implementation does the memcpy in backward direction.
>>>>
>>>> The glibc developers being technically 100% correct is not helping our
>>>> end users in this case though. So we (The Fedora project) need to come up
>>>> with a solution to help our end users, many of whom want to use the adobe
>>>> flash plugin.
>>>>
>>>> This solution could be reverting the problem causing glibc change, or
>>>> maybe changing it to do forward memcpy's while still using the new SSE
>>>> instructions, or something more specific to the flash plugin, as long
>>>> as it will automatically fix things with a yum upgrade without requiring
>>>> any further user intervention.
>>>>
>>>> I would also like to point out that if this were to happen in Ubuntu
>>>> which we sometimes look at jealously for getting more attention / users
>>>> then us, the glibc change would likely be reverted immediately, as that
>>>> is the right thing to do from an end user pov.
>>>>
>>>> I've filed a ticket for FESCo to look into this, as I believe this
>>>> makes us look really bad, and the glibc maintainers do not seem to be
>>>> willing to fix it without some sort of intervention:
>>>> https://fedorahosted.org/fesco/ticket/501
>>>>
>>>> Regards,
>>>>
>>>> Hans
>>> Is someone talking to Adobe about this?
>> Yes, see https://bugs.adobe.com/jira/browse/FP-5739
> Adobe benefits from Flash in Linux. So it seems sensible to:
>
> 1. Get Adobe to commit to a fix soon WITH A $DATE
> 2. Agree to patch the change until $DATE
> 3. Adobe updates Flash, we revert the patch, everyone is happy
I've e-mailed a with Shu Wang at Adobe (who is the assigned contact for
this issue) about a date when they can have this fixed.
You've got the e-mail thread regarding this below:

On 11/17/2010 10:19 AM, Shu Wang wrote:
> Hi Magnus,
>
> Maybe months. Thanks.
>
> Best regards.
> Shu
>
>
> -----Original Message-----
> From: Magnus Glantz [mailto:the-mail-address-is-not-this-one@redhat.com]
> Sent: Wednesday, November 17, 2010 5:15 PM
> To: Shu Wang
> Subject: Re: FP-5739 "Strange sound on mp3 flash website with Fedora 14 x86_64"
>
> Hi Shu,
>
> That's is great to hear. Would you guess it's a matter of days, weeks or
> months before this can get fixed?
> If it will take a long time for you to fix this, Fedora may need to look
> at some way to work around this bug.
>
> Best regards,
> Magnus
>
> On 11/17/2010 10:06 AM, Shu Wang wrote:
>> Hi Magnus,
>>
>> Thanks very much for your information. Flash Player team is investigating on it. It is in progress. Thanks.
>>
>> Best regards,
>> Shu
>>
>>
>>
>> -----Original Message-----
>> From: Magnus Glantz [mailto:the-mail-address-is-not-this-one@redhat.com]
>> Sent: Wednesday, November 17, 2010 4:47 PM
>> To: Shu Wang
>> Subject: FP-5739 "Strange sound on mp3 flash website with Fedora 14 x86_64"
>>
>> Hello Shu,
>>
>> I humbly wonder if you may have a time estimate on fixing FP-5739.
>> It is seriously is affecting the ability to listen to sounds played in
>> Flash for the users of Fedora.
>>
>> The issue has been traced to Adobe Flash by maintainers of glibc at Red
>> Hat, Linus Torvalds and others.
>> You may read more about this issue here:
>> https://bugzilla.redhat.com/show_bug.cgi?id=638477
>>

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Old 11-17-2010, 02:22 PM
Colin Walters
 
Default Fixing the glibc adobe flash incompatibility

On Wed, Nov 17, 2010 at 2:57 AM, Hans de Goede <hdegoede@redhat.com> wrote:
>
> I would also like to point out that if this were to happen in Ubuntu
> which we sometimes look at jealously for getting more attention / users
> then us, the glibc change would likely be reverted immediately, as that
> is the right thing to do from an end user pov.

Hardly; we could for example equally as well patch firefox to load
flash with a compatibility wrapper.
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Old 11-17-2010, 02:22 PM
Colin Walters
 
Default Fixing the glibc adobe flash incompatibility

On Wed, Nov 17, 2010 at 2:57 AM, Hans de Goede <hdegoede@redhat.com> wrote:
>
> I would also like to point out that if this were to happen in Ubuntu
> which we sometimes look at jealously for getting more attention / users
> then us, the glibc change would likely be reverted immediately, as that
> is the right thing to do from an end user pov.

Hardly; we could for example equally as well patch firefox to load
flash with a compatibility wrapper.
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Old 11-17-2010, 02:43 PM
Andrew Haley
 
Default Fixing the glibc adobe flash incompatibility

On 11/17/2010 03:17 PM, Magnus Glantz wrote:
> On 11/17/2010 11:36 AM, nodata wrote:
>> On 17/11/10 10:20, drago01 wrote:
>>> On Wed, Nov 17, 2010 at 10:17 AM, nodata<lsof@nodata.co.uk> wrote:
>>>> On 17/11/10 08:57, Hans de Goede wrote:
>>>>> Hi all,
>>>>>
>>>>> For those who do not know it yet, recent Fedora glibc updates include
>>>>> an optimized memcpy (which gets used on some processors) which breaks the
>>>>> 64 bit adobe flash plugin.
>>>>>
>>>>> The problem has been analyzed and is known, as well as a fix for it, see:
>>>>> https://bugzilla.redhat.com/show_bug.cgi?id=638477
>>>>>
>>>>> The problem still exists however. The glibc developers say that this is
>>>>> not a glibc bug, but a flash plugin bug. And technically they are 100%
>>>>> correct, and the adobe flash plugin is a buggy .... (no surprise there).
>>>>> To be specific the flash plugin is doing overlapping memcpy-s which is
>>>>> clearly not how memcpy is supposed to be used. But the way the flash
>>>>> plugin does overlapping memcpy's happens to work fine as long as one as
>>>>> the c library does the memcpy-s in forward direction. And the new memcpy
>>>>> implementation does the memcpy in backward direction.
>>>>>
>>>>> The glibc developers being technically 100% correct is not helping our
>>>>> end users in this case though. So we (The Fedora project) need to come up
>>>>> with a solution to help our end users, many of whom want to use the adobe
>>>>> flash plugin.
>>>>>
>>>>> This solution could be reverting the problem causing glibc change, or
>>>>> maybe changing it to do forward memcpy's while still using the new SSE
>>>>> instructions, or something more specific to the flash plugin, as long
>>>>> as it will automatically fix things with a yum upgrade without requiring
>>>>> any further user intervention.
>>>>>
>>>>> I would also like to point out that if this were to happen in Ubuntu
>>>>> which we sometimes look at jealously for getting more attention / users
>>>>> then us, the glibc change would likely be reverted immediately, as that
>>>>> is the right thing to do from an end user pov.
>>>>>
>>>>> I've filed a ticket for FESCo to look into this, as I believe this
>>>>> makes us look really bad, and the glibc maintainers do not seem to be
>>>>> willing to fix it without some sort of intervention:
>>>>> https://fedorahosted.org/fesco/ticket/501
>>>>>
>>>>> Regards,
>>>>>
>>>>> Hans
>>>> Is someone talking to Adobe about this?
>>> Yes, see https://bugs.adobe.com/jira/browse/FP-5739
>> Adobe benefits from Flash in Linux. So it seems sensible to:
>>
>> 1. Get Adobe to commit to a fix soon WITH A $DATE
>> 2. Agree to patch the change until $DATE
>> 3. Adobe updates Flash, we revert the patch, everyone is happy
> I've e-mailed a with Shu Wang at Adobe (who is the assigned contact for
> this issue) about a date when they can have this fixed.
> You've got the e-mail thread regarding this below:

So we should be able simply to patch glibc, right? Can't see any reason
not to.

Andrew.

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Old 11-17-2010, 03:32 PM
"Jˇhann B. Gu­mundsson"
 
Default Fixing the glibc adobe flash incompatibility

Dont we have an upstream mantra to uphold...

Forward all Fedora users and otherwize that experience this to Adobe..

If we are going hack around this on our side where are we going to draw
the line..

Are we planning to start hacking around every ill written code out there?

JBG
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Old 11-17-2010, 03:46 PM
Matt McCutchen
 
Default Fixing the glibc adobe flash incompatibility

On Wed, 2010-11-17 at 16:32 +0000, "Jˇhann B. Gu­mundsson" wrote:
> Dont we have an upstream mantra to uphold...
>
> Forward all Fedora users and otherwize that experience this to Adobe..
>
> If we are going hack around this on our side where are we going to draw
> the line..
>
> Are we planning to start hacking around every ill written code out there?

Hopefully not; this is a particularly high-visibility issue. Looking at
https://fedoraproject.org/wiki/Objectives and related pages, Fedora has
to weigh the desire for things to "just work" for the envisioned user
base against the desire not to do something technically inferior to
accommodate non-free software. I'm happy to let FESCo decide this.

--
Matt

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Old 11-17-2010, 04:16 PM
Andrew Haley
 
Default Fixing the glibc adobe flash incompatibility

On 11/17/2010 04:46 PM, Matt McCutchen wrote:
> On Wed, 2010-11-17 at 16:32 +0000, "Jˇhann B. Gu­mundsson" wrote:
>> Dont we have an upstream mantra to uphold...
>>
>> Forward all Fedora users and otherwize that experience this to Adobe..
>>
>> If we are going hack around this on our side where are we going to draw
>> the line..
>>
>> Are we planning to start hacking around every ill written code out there?
>
> Hopefully not; this is a particularly high-visibility issue. Looking at
> https://fedoraproject.org/wiki/Objectives and related pages, Fedora has
> to weigh the desire for things to "just work" for the envisioned user
> base against the desire not to do something technically inferior to
> accommodate non-free software. I'm happy to let FESCo decide this.

Yes. This is not a "one size fits all" problem, and doesn't need a
one size fits all solution. Flash is important to our users.

Andrew.
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Old 11-17-2010, 06:01 PM
Petrus de Calguarium
 
Default Fixing the glibc adobe flash incompatibility

Hans de Goede wrote:

> The problem has been analyzed and is known, as well as a fix for it, see:
> https://bugzilla.redhat.com/show_bug.cgi?id=638477

This worked perfectly on my x86_64 system. I will try later on the i686 laptop.

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Old 11-17-2010, 06:28 PM
Bruno Wolff III
 
Default Fixing the glibc adobe flash incompatibility

On Wed, Nov 17, 2010 at 08:57:20 +0100,
Hans de Goede <hdegoede@redhat.com> wrote:
> Hi all,
>
> For those who do not know it yet, recent Fedora glibc updates include
> an optimized memcpy (which gets used on some processors) which breaks the
> 64 bit adobe flash plugin.

I saw memcpy / memmove issues affecting squashfs-tools shortly before the
F14 alpha. So we had some what of a heads up about the issue over three
months ago. It is unfortunate that we didn't catch the flash issue during
prerelease testing of F14. If this really is an important critera for
releases, maybe we should be having QA testing that flash works.
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