Re: [PATCH v5 2/6] OvmfPkg/PciHostBridgeLib: Init PCI aperture to 0

[Laszlo Ersek <lersek@redhat.com>]

On 03/01/18 13:03, Ni, Ruiyu wrote:
> On 3/1/2018 6:20 PM, Laszlo Ersek wrote:
>> On 03/01/18 07:57, Heyi Guo wrote:
>>> Use ZeroMem to initialize all fields in temporary
>>> PCI_ROOT_BRIDGE_APERTURE variables to zero. This is not mandatory but
>>> is helpful for future extension: when we add new fields to
>>> PCI_ROOT_BRIDGE_APERTURE and the default value of these fields can
>>> safely be zero, this code will not suffer from an additional
>>> change.
>>>
>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>> Signed-off-by: Heyi Guo <heyi.guo@linaro.org>
>>>
>>> Cc: Jordan Justen <jordan.l.justen@intel.com>
>>> Cc: Anthony Perard <anthony.perard@citrix.com>
>>> Cc: Julien Grall <julien.grall@linaro.org>
>>> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
>>> Cc: Laszlo Ersek <lersek@redhat.com>
>>> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>> ---
>>>   OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c | 4 ++++
>>>   OvmfPkg/Library/PciHostBridgeLib/XenSupport.c       | 5 +++++
>>>   2 files changed, 9 insertions(+)
>>
>> I also suggest a different subject line:
>>
>> OvmfPkg/PciHostBridgeLib: clear PCI_ROOT_BRIDGE_APERTURE vars for
>> (re)init
>>
>> (74 chars)
> 
> I sometimes tries very hard to make the subject line be <= 70 chars.
> 74 is acceptable?

To my knowledge, the Linux kernel development guidelines suggest
wrapping the commit message body at 74 characters, and IIRC the same
limit applies to the subject line. I tend to follow these ideas for edk2
development too.

I think anything under 74 chars (for the subject) is an unreasonable
expectation for edk2. First, we start with a prefix of the form

  XxxPkg/Module: ...

Sometimes this prefix is incredibly long alread :/ So what I do (and I
guess most others do as well) is that I first write an "honest" subject
line (which frequently reaches 90-100 chars), and then work on
compressing it down to 74 characters. Sometimes it becomes a real
struggle, with strange abbreviations etc. I might make an exception and
go up to 75-76, and hope that nobody notices :) So, in that range,
limiting ourselves to 70 chars would be catastrophic.

Thanks!
Laszlo