Re: [PATCH edk2-platforms v1 13/14] Hisilicon/Library: Add OsBootLib

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 29 January 2018 at 08:55, Huangming (Mark) <huangming23@huawei.com> wrote:
>
>
> On 2018/1/27 18:37, Ard Biesheuvel wrote:
>> On 27 January 2018 at 01:47, Huangming (Mark) <huangming23@huawei.com> wrote:
>>>
>>>
>>> On 2018/1/23 18:23, Leif Lindholm wrote:
>>>> On Thu, Jan 18, 2018 at 11:01:42PM +0800, Ming Huang wrote:
>>>>> OsBootLib can create OS option after upgrade firmware.
>>>>
>>>> I will respond more strongly that Ard did:
>>>>
>>>> I have seen functionality like this implemented in publicly available
>>>> systems - laptops, desktops.
>>>> Without exception, they end up in bug reports saying "my system
>>>> refuses to boot after installation/upgrade".
>>>> Without exception, they add to existing negative perceptions of UEFI
>>>> in general in certain market spaces.
>>>>
>>>> Presumably this is trying to address a real problem you have faced.
>>>> Please bring this issue to the table for discussion, so that we can
>>>> agree on an appropriate way of resolving it.
>>>>
>>>> Regardless, this code will not be included in 18.02.
>>>>
>>>> /
>>>>     Leif
>>>>
>>>> .
>>>>
>>>
>>> The problem is that OS boot option is lost after upgrade firmware.
>>
>> Why is that? There is no need to clear the variable store if you
>> upgrade the executable image. If you fix this issue, you don't need
>> this patch.
>>
>
> Ok, retaining the variable store can solve the problem also.
> But retaining the variable store have some issues, like,if the struct stored in
> variable is different between new firmware and old firmware, this situation may cause
> a problem.
>

Yes. That means you have to design it with forward compatibility in
mind, i.e., add reserved fields that default to zero, and use zero as
a reasonable default when you add new fields.

> If OsBootLib is not needed for community, It will use for internal project in hisilicon.
>

Well, that is up to you to decide. But I highly recommend not
hardcoding this kind of knowledge into the firmware to begin with.

>
>>> It is inconvenient for using. OsBootLib can help this.
>>>
>>> OsBootLib retain the options installed by OS, and create OS boot option
>>> after upgrade firmware if grub file is existed in EFI partition and in mUefiOsBootFiles,
>>> and delete redundant options in the same GPT.
>>>
>>
>> .
>>
>
> --
> Best Regards,
>
> Ming
>