Programmable Devices
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19997 Discussions

why DMESG command showing more memory is mapped to a bar than actual size ??

Honored Contributor II



This is on s10. I have a IP which is a MM-avalon slave of just 8 bytes. when i connect this to bar2 (using s10 HardIP pcie from IP catalog). By default the address range for this IP is 0x0 to 0x7 and it shows an error saying- size of bar should be greater than 7 bits.  


I realized and edited the address tab section and adjusted 0x4000 - 0x4007 , this caused size bits on bar2 went to 13 and the dmesg command on host says that bar2 mapped to 32kB. 

if i change it to 0x10_0000 - 0x10_0007 then size bits become 21 bits and the dmesg command on host says that bar2 mapped to 2 MB. but the IP itself is just a 8 bytes IP.  

why cant dmesg shows bar2 mapped to 8 bytes. ? one can observe that size depends on the address lines required to represent base address but the range remains same i.e 8 bytes. 


what i am missing here ?? 


Thank you.
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