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Old 07-18-2014, 07:59 AM   #1
stf92
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Making a memory dump in Linux?


Hi: by memory I mean the main processor's memory (RAM or ROM). Is there a Linux utility that can dump memory to stdout? As a second question, where is the video memory located, assuming the video controller shares the main processor memory and that it is in text mode?
 
Old 07-18-2014, 08:45 AM   #2
smallpond
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Question 1 - if you mean physical memory:

Code:
dd if=/dev/mem bs=1 seek=start_addr count=size
Question 2 - That would depend on your video driver. I don't believe that the kernel keeps a buffer of what's on a text-based screen, it just sends characters to the lower-level tty driver.
 
Old 07-18-2014, 09:08 AM   #3
stf92
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Thanks. I think to be able to make the dump human readable I should include of=<some_file> in the dd comand and then see the file with for example hexdump. Writing directly to stdout would fill the screen with garbage, I assume.

As to the video memory, I remember in the PC compatibles, it was in the 0xB000 or 0xB800 segment. The video controller swept this memory region. If at B000:0 there was 0x41, then you would be seen an 'A' in the upper left corner of your screen.
 
  


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