It's just an experience value and has been here about 10 years...

Which usb brand/model name do you have problem on?


-----Original Message-----
From: Heyi Guo [] 
Sent: Wednesday, October 19, 2016 9:57 AM
Cc: Tian, Feng <>; Zeng, Star <>
Subject: [edk2] Why is USB_BOOT_IO_BLOCKS set to 128?

Dear experts,

Could anyone help to explain why USB_BOOT_IO_BLOCKS in 
MdeModulePkg/Bus/Usb/UsbMassStorageDxe/UsbMassBoot.h is set to 128?

We found on some platforms this value may cause USB boot failure and
*64* blocks will make them work. Though we have not got the final root cause, 
it will be really helpful if you can tell the reason of setting it to 128 and 
possible root cause for such issue.

Thanks and regards,


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