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''SysRq debugger'' can help you to obtain some information from oops-ed kernel. This feature is available since 026test017 kernel. | ''SysRq debugger'' can help you to obtain some information from oops-ed kernel. This feature is available since 026test017 kernel. | ||
| − | == Features == | + | == Features == |
''SysRq debugger'' can do one of the following: | ''SysRq debugger'' can do one of the following: | ||
# Dump memory at specified address | # Dump memory at specified address | ||
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# Resolve symbol address by its name | # Resolve symbol address by its name | ||
| − | == How to use it == | + | == How to use it == |
To enter debug mode press ''SysRq-g''. | To enter debug mode press ''SysRq-g''. | ||
After this the following commands will be available: | After this the following commands will be available: | ||
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# ''SysRq-q'' - quit debugger | # ''SysRq-q'' - quit debugger | ||
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After entering ''-d'', ''-w'' or ''-r'' state you must enter address to work with (and the value you want to write if you do). Simply do this by pressing according keys while holding ''Alt-StsRq''. | After entering ''-d'', ''-w'' or ''-r'' state you must enter address to work with (and the value you want to write if you do). Simply do this by pressing according keys while holding ''Alt-StsRq''. | ||
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If you need to enter the upper case letter or the underbar (<code>_</code>) while typing a symbol name then you need to press and release ''shift'' and then the letter or minus (<code>-</code>). | If you need to enter the upper case letter or the underbar (<code>_</code>) while typing a symbol name then you need to press and release ''shift'' and then the letter or minus (<code>-</code>). | ||
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At the end press ''enter''. | At the end press ''enter''. | ||
| − | == Working with proc == | + | == Working with proc == |
There is a <code>/proc/sysrq-trigger</code> entry which triggers sysrq events. | There is a <code>/proc/sysrq-trigger</code> entry which triggers sysrq events. | ||
You may write a string to it to trigger commands one by one. | You may write a string to it to trigger commands one by one. | ||
There is one note: the string must end with the <code>\r</code> character. | There is one note: the string must end with the <code>\r</code> character. | ||
| − | == Examples == | + | == Examples == |
Here are some examples of how to use debugger | Here are some examples of how to use debugger | ||
| − | === Dump memory === | + | === Dump memory === |
<pre> | <pre> | ||
# echo -n -e 'gd0xc0000000\rq' > /proc/sysrq-trigger | # echo -n -e 'gd0xc0000000\rq' > /proc/sysrq-trigger | ||
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will dump memory region of 512 bytes | will dump memory region of 512 bytes | ||
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<pre> | <pre> | ||
# echo -n -e 'gxq' > /proc/sysrq-trigger | # echo -n -e 'gxq' > /proc/sysrq-trigger | ||
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will dump the next 512 bytes of memory | will dump the next 512 bytes of memory | ||
| − | === Write to memory === | + | === Write to memory === |
<pre> | <pre> | ||
# echo -n -e 'gw0xc0000000-0x12345678\rq' > /proc/sysrq-trigger | # echo -n -e 'gw0xc0000000-0x12345678\rq' > /proc/sysrq-trigger | ||
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will write ''0x12345678'' at ''0xc0000000'' | will write ''0x12345678'' at ''0xc0000000'' | ||
| − | === Resolve symbol === | + | === Resolve symbol === |
<pre> | <pre> | ||
# echo -n -e 'grschedule\rq' > /proc/sysrq-trigger | # echo -n -e 'grschedule\rq' > /proc/sysrq-trigger | ||
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will print you an address ''schedule()'' function starts from | will print you an address ''schedule()'' function starts from | ||
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<pre> | <pre> | ||
# echo -n -e 'gxq' > /proc/sysrq-trigger | # echo -n -e 'gxq' > /proc/sysrq-trigger | ||
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will dump first 512 bytes of it | will dump first 512 bytes of it | ||
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Note <i>''-n''</i> and <i>''-e''</i> keys to ''echo'' command. | Note <i>''-n''</i> and <i>''-e''</i> keys to ''echo'' command. | ||
</translate> | </translate> | ||
