On 2019/05/28 22:42, Petr Mladek wrote: >> Ahh.. OK, now I sort of remember why I gave up on this idea (see [1] >> at the bottom, when it comes to uv_nmi_dump_state()) - printk_NMI and >> printk-safe redirections. >> >> NMI >> loglevel = NEW >> printk -> printk_safe_nmi >> loglevel = OLD >> >> iret >> >> IRQ >> flush printk_safe_nmi -> printk >> // At this point we don't remember about >> // loglevel manipulation anymore >> iret > > printk_safe buffer preserves KERN_* headers. It should be > possible to insert KERN_UNSUPPRESSED there.
But is context dependent buffer large enough to hold SysRq-t output? I think that only main logbuf can become large enough to hold SysRq-t output. We can add KERN_UNSUPPRESSED to SysRq's header line. But I don't think that we can automatically add KERN_UNSUPPRESSED to SysRq's body lines based on some context information. If we want to avoid manipulating console_loglevel, we need to think about how to make sure that KERN_UNSUPPRESSED is added to all lines from such context without overflowing capacity of that buffer.
