Hi Steve, Daniel, On Tue, 2020-11-24 at 11:37 -0500, Steven Rostedt wrote: > Hi Tom, > > Daniel asked about filtering bitmasks, something like: > > cpumask != 0xff > > Looking into the code, I realized that bitmasks are dynamic arrays, > and > there's no logic in the filter code to handle dynamic arrays of > anything > other than 'char' type (which are dynamic strings). > > If you have any cycles to spare, do you think you can add code to > process > dynamic arrays other than char? > > The compare logic may be complex though. I think the above example > should > work, but we would need to define how that happens. > > I guess we should follow the cpumask logic, and break all non string > dynamic arrays up into 32 bit words. Even if something is defined as > u8, it > will be converted to the local endian of the machine. Basically, we > should > follow the function bitmap_string() defined in lib/vsnprintf.c > > If we have a u8 dynamic array of: > > 0x12 0x34 0x56 0x78 0x9a 0xbc 0xde 0xf0 > > On a little endian machine it would match: > > 0xf0debca9,0x78563412 > > This way, if we have a machine with 64 CPUS, and we want to match > cpus 0-7, > then we only need to do: > > cpumask & 0xff > > The above would be equivalent to: > > cpumask & 0,0xff > > in such a case. > > That's because, if I'm reading the code correctly, a cpumask for CPUs > 0-7 > bits set for 64 CPU machine in raw format would be: > > 0x00 0x00 0x00 0xff 0x00 0x00 0x00 0x00 > > The dynamic arrays will allow comma separated 4 byte words to match. > > Daniel brought this up, and he said he'd be willing to help out > making a > patch if he has spare cycles to spare. Perhaps, between the two of > you, you > could come up with the cycles to produce such a patch :-) >
Sure, I can take a look - luckily holidays are coming up so should be able to find some time for this. Tom > Cheers, > > -- Steve
