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Date:      Fri, 15 Mar 2019 09:27:49 -0700
From:      John Baldwin <jhb@FreeBSD.org>
To:        cem@freebsd.org, Andrew Thompson <andy@fud.org.nz>
Cc:        src-committers <src-committers@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, svn-src-head <svn-src-head@freebsd.org>
Subject:   Re: svn commit: r345171 - head/usr.sbin/bhyve
Message-ID:  <5adee283-2cac-14d2-ec06-bce43bf3bcde@FreeBSD.org>
In-Reply-To: <CAG6CVpVYyWywKFtqtgayghkrEptmDEP3dm%2BwWE0t7MDqyHXvUw@mail.gmail.com>
References:  <201903150211.x2F2BSai079898@repo.freebsd.org> <CAFAOGNTT_ZKCe1zs2XN6H7r-G2E%2BU77WUOrutfWshDNGOR36bQ@mail.gmail.com> <CAG6CVpVYyWywKFtqtgayghkrEptmDEP3dm%2BwWE0t7MDqyHXvUw@mail.gmail.com>

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On 3/14/19 10:24 PM, Conrad Meyer wrote:
> On Thu, Mar 14, 2019 at 8:06 PM Andrew Thompson <andy@fud.org.nz> wrote:
>>
>> On Fri, 15 Mar 2019 at 15:11, Chuck Tuffli <chuck@freebsd.org> wrote:
>>>         bzero(&pciecap, sizeof(pciecap));
> ...
>>> +               pciecap.dev_capabilities = PCIEM_CAP_ROLE_ERR_RPT;
>>
>> If the message you say 'set the bit' but you are overwriting the whole variable, is this intended?
> 
> Looks like it was zero before.  So yeah, it sets the bit.

It would probably be cleaner for future changes to make it a |=, but that's a
tiny nit.  style(9) wants a blank line before the comment as well.

I hadn't approved it yet only because I hadn't gone and dug through my PCIe
books / specs to see what this bit is and confirm it is required.

OTOH, it's not clear to me that bhyve PCI-e devices don't want to just be 1.0a
devices as a lowest common denominator to be as accommodating to as wide variety
of OS's as possible.

One thing I didn't see in a review was a reason for why to make this change?
Does some OS reject devices without this bit set or is it just based on reading
the spec?  bhyve doesn't assert any PCI-e errors for virtual devices, so
this bit is pretty meaningless.

-- 
John Baldwin



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