Re: [edk2-devel] [PATCH V1 1/1] OvmfPkg/QemuBootOrderLib: Measure the etc/boot-menu-wait

["sunceping" <cepingx.sun@intel.com>]

On Friday, March 22, 2024 5:06 PM Gerd Hoffmann wrote:
> 
> > > But then you have to find and update all callsites (or at least the
> > > ones where we care about measurement).
> > In your solution,  if we cache all items that need to be measured, we
> > would have to add a new API (example: QemuFwCfgGetDataFromCache ())  to
> get the data from cache.
> 
> No, we only need to update QemuFwCfgSelectItem + QemuFwCfgReadBytes to
> support reading from the cache.
Do you mean the existing API (QemuFwCfgSelectItem + QemuFwCfgReadBytes) need to be changed to support reading from the cache?

If that is the case,  there are some concerns as below:
1:  One or more new parameters (of QemuFwCfgReadBytes())  need to be added to search 
the item in cache, which is equivalent to adding a new API.

2:  The current QemuFwCfgReadBytes can read in chunks from qemu (example etc/e820) 
If we call QemuFwCfgReadBytes to get data from cache , we also need to support reading in chunks.
Then we have to add more parameters ( to set offset). This will make the API more and more complicated.

> QemuFwCfgGetDataFromCache() can be added as additional API, and callsites have the option to either switch over, or continue to use the existing API.
Base above concerns, we think QemuFwCfgGetDataFromCache is must.

Thanks
Ceping




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