procfs - synthetic /proc filesystem

src/kernel/include/kernel/procfs.h + src/kernel/arch/i386/fs/procfs.c.

Purpose

Linux-style read-only view of kernel state. Each entry is generated on read by a small renderer that walks live kernel state and writes ASCII into the caller’s buffer. No on-disk storage; nothing is cached between reads.

Entries

Path Renderer Content
/proc/cpuinfo CPUID leaves 0 + 1 vendor_id, cpu family, model, stepping, flags (fpu/tsc/msr/pae/apic/cmov/mmx/sse/sse2/sse3/sse4_1/sse4_2), arch i386 (protected mode)
/proc/meminfo pmm_managed_count() + pmm_free_count() + heap_used/free() Linux-style key/value: MemTotal, MemFree, MemAvailable, MemUsed, Buffers (0), Cached (0), HeapTotal, HeapUsed, HeapFree, PageSize, FreeFrames, TotalFrames. MemTotal reflects the bootloader-available frame pool minus the null page + kernel image (cached at pmm_init). MemUsed folds in HeapUsed (and MemFree subtracts it): the 16 MiB kernel heap is identity-mapped on top of PMM frames the allocator never reserved, so without this it read near-zero on a fresh boot.
/proc/tasks Walk task_pool[], skip TASK_DEAD PID NAME STATE TTY TICKS MEMKB CWD. MEMKB is the per-task memory: the 8 KiB kernel stack plus resident user pages (vmm_count_user_pages(page_dir) * 4), so kernel-only tasks (idle, shells) report their stack baseline and ring-3 apps report stack + RSS. Dead-but-not-yet-reclaimed slots are filtered so userspace tools (maktop / cat /proc/tasks) only see live work; TASK_ZOMBIE slots (slice 16b: children awaiting parent wait4) DO appear so the parent can see them.
/proc/uname MAKAR_VERSION + build macros + timer_get_ticks() Makar <MAKAR_VERSION> (i386) built <date> <time> + uptime ticks
/proc/rtc CMOS RTC read One line YYYY-MM-DD HH:MM:SS (local wall-clock). Read by the GUI dock clock/date tray, the mxclock/clock apps, and about/hwspecs.

VFS integration

Wired in vfs.c as a new backend (VFS_FS_PROC = 3):

  • vfs_route() recognises any path under /proc.
  • vfs_ls("/proc") calls procfs_ls() to print the entry list.
  • vfs_cat() / vfs_read_file() route to procfs_read_file().
  • vfs_complete() lets tab-completion enumerate /proc/<entry>.
  • vfs_file_exists() returns 1 for known entries.

procfs is flat (no subdirectories) and read-only (no vfs_write_file path). cd /proc is allowed; cd /proc/cpuinfo is rejected as not-a-dir.

Adding a new entry

  1. Add a PROC_XXX enum value and an entry to the s_entries[] table.
  2. Write a render_xxx(pf_writer_t *w) function using pf_puts, pf_putu, pf_putc.
  3. Add a dispatch case in procfs_read_file.

No changes to vfs.c are needed.